How Does Night Shift Work Impact Health?
Did you know that our ancestors were nocturnal? They used to stay awake in the night to hunt without worrying about dangerous predators and sleep during the day. Now, our circadian rhythms are lined up with the sun. That's why as soon as the sun sets, our bodies start getting ready for rest, and we end up feeling sleepy.
Circadian rhythms are biological cycles that coordinate essential mental and physical functions, such as sleep and hunger. The circadian clock is regulated by a part of the brain called the Suprachiasmatic Nucleus (SCN).
The circadian clock is also influenced by temperature. When the body temperature drops around the afternoon and late evening, it induces drowsiness and sleep.
Sleep is induced by a hormone called melatonin, which is produced in low-light conditions. Bright light conditions during the day suppress melatonin production and promote wakefulness.
People who work the night shift have disrupted circadian rhythm and have an increased risk for the following conditions:
- Obesity
- Cardiovascular diseases
- Mood changes
- Digestive issues like diarrhea, constipation, stomach discomfort, peptic ulcers
- Cancers, especially breast cancer
- Epilepsy in people who are predisposed to the condition
- Sleep problems
- Chronic fatigue
- Depression
Working the night shift is carcinogenic to humans, according to multiple studies conducted the world over.
Several studies show that disruption in the night’s sleep can reduce melatonin levels and increase the risk of tumor growth.
Night Shift Work—A Risk Factor for Breast Cancer
Some animal studies have shown that exposure to light at night led to the growth of breast cancer.
The risk of breast cancer among nurses and other night-shift workers seems to be higher than their counterparts who worked day shifts.
A study published in the Journal of National Cancer Institute in 2001 reported that women who work in rotating night shifts for at least three nights per month, along with day shifts, have a moderately high risk of breast cancer.
Further, the risk seems to be higher when the night shifts per week increase!
This increased risk is attributed to the messed-up melatonin levels in the body.
In addition to promoting sleep, melatonin also stops tumor growth and protects against the spread of cancer cells.
When melatonin levels decrease in the body, it results in an imbalance of inflammatory cytokines, increased mutations in the cells, and oxidative damage (due to free radicals).
These events can all trigger cancer development.
A reduction in melatonin also affects estrogen levels, which further increases the risk of breast cancer.
How Does Genetics Influence Rotating Night Shift Work and Breast Cancer Risk?
A long duration of shift work throughout the years is associated with estrogen and progesterone-positive tumors.
When the circadian rhythm is altered, it changes the expression of the CLOCK genes. This also influences the production of reproductive hormones.
The NPAS2 Gene
The Neuronal PAS Domain Protein 2 or NPAS2 gene is the largest circadian gene. It plays a vital role in sleep homeostasis and circadian rhythm regulation.
This gene also regulates the cell cycle and works with certain other genes for repairing DNA. The NPAS2 gene shows a strong association with breast cancer.
rs2305160 (Ala394Thr) is an SNP (Single Nucleotide Polymorphism) in the NPAS2 gene.
Among women with little or no exposure to shift work, the A allele (AA or AG) is associated with a significantly lower risk of breast cancer.
However, among women with AA genotype who had worked >2 years of rotating night shifts, the risk of breast cancer was nearly 3 fold compared to women with the same genotype with <2 years of night shift work.
| Genotype | Implication - > 2 years of rotating night shifts |
| AA (Thr/Thr) | ~3 fold increased risk of breast cancer |
| AG (Thr/Ala) | Slightly increased risk of breast cancer |
| GG (Ala/Ala) | Normal risk of breast cancer |
Use Xcode Life’s Free Gene Tool To Find Out If You Have The Risk Genotype!
The RORA Gene
RAR-Related Orphan Receptor A or the RORA gene is located on chromosome 15 and regulates genes involved in the body’s circadian rhythm.
rs1482057 is an SNP in the RORA gene. A study published in 2014 showed that SNP rs1482057 was associated with breast cancer in postmenopausal women.
Women who have at least one A allele and had a history of working night shifts in their lifetime had a higher risk of developing breast cancer.
Conversely, women having the CC genotype and working night shifts showed a decreased risk of breast cancer.
| Genotype | Implication |
| AA | Increased breast cancer risk on night shift work |
| AC | Increased breast cancer risk on night shift work |
| CC | Decreased breast cancer risk on night shift work |
The CRY2 Gene
Cryptochrome circadian regulator 2 or the CRY2 gene gives instructions to produce a protein involved in regulating the body’s circadian rhythm.
rs2292912 is an SNP in the CRY2 gene, located on chromosome 11. Night shift working increased the risk of breast cancer in women who carried the CG genotype of rs2292912 SNP.
| Genotype | Implication |
| CG | Increased breast cancer risk on night shift work |
| GG | Decreased breast cancer risk on night shift work |
| CC | Decreased breast cancer risk on night shift work |
Regulating Your Sleep-Wake Cycle To Reduce Breast Cancer Risk
- Reduce your night shift hours per week
Since working night shift hours increases the risk of breast cancer in women, one of the most effective ways to lessen this risk is to reduce working night shifts.
Switching with a colleague’s shift, alternating your night shifts with day shifts, or switching jobs can be a few ways by which you can reduce your night shift hours.
- Get a minimum of 7-8 hours of sleep every day
Apart from disrupting the sleep-wake cycle, disturbed sleep or poor quality of sleep in people who work night shifts can increase their risk for breast cancer.
So, if you are working a night shift, ensure you get your 7-8 hours of sleep every day. If you have trouble sleeping, consult your doctor about supplements that can help you catch up on your daily sleep.
- Reduce other risk factors for breast cancer
People working the night shift must try and reduce other risk factors of breast cancer.
A healthy diet with lots of fruits, limited alcohol consumption and smoking, adequate physical activity, and reduced exposure to harmful chemicals can help reduce breast cancer risk.
Summary
- The circadian rhythm regulates our body’s sleep-wake cycle.
- A disturbed circadian rhythm increases the risk of developing health conditions like obesity, cardiovascular diseases, gastrointestinal problems, etc.
- According to many studies and published reports, working the night shift is carcinogenic as it decreases melatonin production - melatonin helps stop tumor growth.
- Working the night shift has been particularly associated with an increased risk for breast cancer.
- Women with certain changes in genes like NPAS2, RORA, and CRY2 have an increased risk of breast cancer when on rotating night shifts.
- Regulating your sleep-wake cycle, getting adequate sleep, following a healthy diet, and limiting alcohol consumption and smoking can help lower breast cancer risk.
Reference:
- https://pubmed.ncbi.nlm.nih.gov/28541391/
- https://academic.oup.com/jnci/article/93/20/1563/2519563
- https://pubmed.ncbi.nlm.nih.gov/19095474/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405398/
- https://cebp.aacrjournals.org/content/27/1/25
- https://blogs.cdc.gov/niosh-science-blog/2021/04/27/nightshift-cancer/
- https://academic.oup.com/jnci/article/93/20/1563/2519563
- https://www.frontiersin.org/articles/10.3389/fonc.2020.01006/full
- https://www.uniprot.org/uniprot/Q99743
Abstract
Night shift work can impact your circadian rhythm by making you operate in a way that is “unnatural” to your sleep-wake cycle. A recent study has reported that people who work night shifts are at an increased risk of developing atrial fibrillation and heart disease. The study further reported that among the night shift workers, women who are physically inactive are at the highest risk.
What is Atrial Fibrillation?
Atrial fibrillation (AF) is characterized by irregular and often rapid heart rate that can increase the risk of stroke, heart failure, and other heart-related ailments.
Generally, the chambers of the heart work in coordination to pump the blood. However, in AF, the two upper chambers of the heart (right auricle and left auricle) beat chaotically and out of coordination with the two lower chambers (right and left ventricle) of the heart.
Some common symptoms associated with AF include :
- Pain in the chest
- Dizziness
- Fatigue
- Shortness of breath
- Fast heart rate or palpitations
Learn Your Genetic Risk for Atrial Fibrillation with Xcode Life’s Gene Health Report
Night Shift And Heart Disease
Night shift workers, on average, get two to three hours less sleep than other workers. They often sleep through the day in two split periods; a few hours in the morning and then around an hour before starting the night shift.
It’s challenging to keep the sleep environment dark, free of noise, and relatively calm. A person working the night shift is at greater risk of various health conditions due to the disrupted circadian rhythm.
Researchers suggest that working the night shift may lead to hormonal and metabolic changes, which can increase the risk for obesity, diabetes, and heart disease.
Further, studies report that circadian misalignment results in a drop in levels of the weight-regulating hormone leptin. This can increase heart disease risk by prompting an increase in appetite.
The Study: Night Shift Work and Heart Problems
The study included 286,353 people who were in paid employment or self-employed.
The study cohort was divided into:
- 283,657 did not have AF when they enrolled (out of which genetic information was available for 193,819)
- 276,009 did not have heart failure or stroke (out of which employment history information was provided by 73,896)
- 75,391 who answered a questionnaire about their lifetime employment in 2015
- 5,777 who developed AF in a follow-up time of over ten years
The researchers adjusted their analyses for several factors like age, sex, ethnicity, education, socio-economic status, diet, smoking, body mass index, sleep duration, and chronotype that could alter the risk of developing AF.
The researchers, therefore, adjusted these risk factors.
The following were observed in the study:
- People who are currently working night shifts have a 12 % increased risk of developing AF.
- For those who had a lifetime duration of night shifts, the risk increased to 18% after ten or more years.
- People who worked night shifts three to eight times a month for ten years have a 22% increased risk of developing AF.
- The risk of coronary heart disease for the above three groups was 22%, 37%, and 35%, respectively.
The study further revealed two more interesting findings.
- Women had a 64% increased risk of developing AF than men when they worked night shifts for ten or more years.
- People who performed 150 minutes of moderate-intensity physical activities or 75 minutes of vigorous-intensity activities per week had a lower risk of developing AF.
How To Work The Night Shift and Stay Healthy
Avoid Caffeine Close to Bedtime
Caffeine inhibits your body’s ability to feel sleepy. So, avoid food and drink containing caffeine at least 4 hours before your bedtime.
Maintain A Sleep-Conducive Environment In Your Bedroom
Light exposure can activate all the processes in your body associated with wakefulness, making it difficult for you to fall asleep. Use blackout curtains or blinds that can help block the light entry.
Eat Healthy
Shift work has been associated with an increased risk of metabolic disorders. Limit sugar intake and increase protein intake. Eating small, frequent meals can also help maintain your metabolic health.
Exercise Regularly
Avoid daytime exercising when on shift work, as it can promote wakefulness. But, make sure to adopt a consistent exercise routine as this can help lower the risk for heart disease.
Video
Summary
- Atrial fibrillation is a condition characterized by an irregular and often rapid heart rate.
- A recent study explored the link between night shift work and atrial fibrillation.
- According to the study, people who worked night shifts over an extended period have an increased risk of atrial fibrillation than the day workers.
- Among shift workers, women who are not physically active seem to have the highest risk for Atrial Fibrillation.
- Following a healthy diet, good sleep hygiene, and a consistent workout routine can help maintain your health when on a night shift job.
References
- https://www.sciencedaily.com/releases/2021/08/210816111941.htm
- https://www.heart.org/en/health-topics/atrial-fibrillation/what-is-atrial-fibrillation-afib-or-af
- smart.servier.com
What Is A Chronotype?
Research shows that your bedtime may actually be linked to your DNA! Everyone’s biological clock is wired differently; it’s not in sync. Environmental and genetic factors affect your circadian rhythm, or your internal clock. Circadian rhythms, in turn, influence your sleeping pattern.
Your preferred sleeping pattern is called your ‘chronotype.’ Going to sleep around 11 PM and waking up around 7 AM puts you in the average chronotype category. Someone with an average chronotype gets roughly the same amount of sleep on both working and non-working days, and this is good.
About 40% of the population does not belong to this category. They have late or early chronotypes. These people will find it pretty difficult to go to work after a free day. They may even experience symptoms of jet lag.
What contributes to the difference in chronotypes?
Melatonin: The Sleep Hormone
Melatonin is the "sleep hormone" that regulates the sleep-wake cycle in the body. It is produced by a neuron bundle called Suprachiasmatic Nucleus or SCN for short.
For people with the average chronotype, melatonin production starts around 9 PM, and the whole body enters into the 'rest mode' by 10:30 PM. The body temperature enters its lowest around 4:30 AM. These people usually wake up around 6:45 AM when the blood pressure spikes to the highest point. They are known as the 'early risers' and are alert and active during the daytime.
For people with the late chronotype, this whole cycle happens later during the day. As a result, they tend to sleep and wake up much later.
They may not entirely be able to fix this. This is because the CLOCK genes found in the SCN neuron bundle regulate the 24-hour cycle in your body. Changes in the CLOCK genes influence your chronotype status - average, or early, or late.
A study was carried out on hamsters to study the contributing factors to chronotype. Scientists replaced the SCN of early chronotype hamsters with that of average chronotype hamsters. To their surprise, the hamsters still went to sleep and woke up early, according to their early chronotype.
This is because, other than the SCN clock, the body also contains other biological clocks, all of which contribute to a person’s chronotype. And, this is why it can be very difficult to break out of your natural sleeping pattern.
Chronotype Genetic Test
To know what your chronotype is based on your genes, you can get a genetic test done. Most genetic tests provide your DNA information in the form of a text file called the raw DNA data. At Xcode Life, can help you interpret this data.
All you have to do is upload your raw data and order a sleep report. Xcode Life then analyzes your raw data in detail to provide you with a comprehensive sleep analysis, including information on your chronotype and risk for various sleep disorders.
Video
Introduction: What Is Snoring?
Snoring is the loud or harsh sound from the nose or mouth that occurs when breathing is partially obstructed. The sound is produced when the soft palate and other soft tissues (such as uvula, tonsils, nasal turbinates, and others) in the upper airway vibrate.
Affecting nearly 90 million Americans, it can lead to disturbed, unrefreshing sleep, ultimately resulting in poor daytime function. Snoring is caused due to obstruction of air passage, resulting in the vibration of respiratory structures and the production of sound during breathing while asleep.
Snoring is more prevalent in males than in females. Certain risk factors such as genetic predisposition, throat weakness, obesity, mispositioned jaw, obstructive sleep apnea, sleep deprivation, alcohol consumption, and mouth breathing are associated with snoring.
How Do Genes Influence Snoring Risk?
Twin and family studies have identified the association between genetic factors and snoring risk, with heritability ranging between 18 to 28%.
A recent study published in 2019 leveraged data from a large U.K. Biobank study consisting of the Australian adult population to identify the molecular mechanisms associated with snoring.
MSRB3 Gene and Snoring
MSRB3 is associated with protein and lipid metabolism pathways, which are related to hippocampal volume (a region in the brain) and lung function. Such genetic associations are consistent with the findings that severe bouts of snoring may be due to:
- Nocturnal oxygen desaturation (temporary drop in oxygen levels in hemoglobin)
- Lowered neuropsychological functions, with reduced ability to consolidate memory.
rs10878269 And Snoring
The rs10878269 is G>A polymorphism located in the MSRB3 gene. A study by Jones, Samuel E., et al.2016 showed that variant rs10878269 was significantly associated with reduced snoring risk.
Non-genetic Influences On Snoring
- Mouth anatomy* : A low, thick, and soft palate can narrow down the airway and may result in snoring
- Nasal problems : Deviated nasal septum and nasal congestion can contribute to snoring.
- Sex : Men are more likely to snore or have sleep apnea than women.
- Obesity : Fatty tissues in the neck of obese/overweight people can narrow the airways and cause snoring.
- Sleep Deprivation : Not getting enough sleep can lead to throat relaxation.
Effects Of Snoring
Snoring is not often considered a serious health concern except in some conditions. Snoring can usually be cured through simple home remedies. Light and infrequent snoring is completely normal. Snoring that is linked to obstructive sleep apnea (OSA) is, however, worrisome and needs to be treated.
Tips For A Snore-free Sleep
- Reduce the consumption of alcohol and sedatives as this relaxes your muscles and leads to snoring.
- Maintain your weight as obesity and being overweight are risk factors for snoring and sleep apnea.
- Change your sleeping position. When you sleep on your back, your airway has higher chances of getting blocked. Sleeping on your side, raising your head by a few inches, or using a pillow to improve your neck position are a few alternative sleep positions to try.
- Relieve nasal congestion before you sleep.
- Anti-snoring mouthpieces can be used to hold your jaw and tongue in a suitable position to prevent blockage of the airway,
- Throat exercises can help strengthen the muscles and prevent them from collapsing during sleep.
- Try to quit smoking. Smoking can result in inflammation in the upper airway passage, and this blocks airflow.
Video
Summary
- Snoring is a common sleep disorder that affects over 90 million Americans. It is characterized by a loud noise from the nose/mouth due to an obstructed airway.
- Genetic predisposition, throat weakness, obesity, mispositioned jaw, obstructive sleep apnea, sleep deprivation, alcohol consumption, and mouth breathing are some risk factors associated with snoring.
- The MSRB3 gene, associated with protein and lipid metabolism pathways related to lung function and hippocampal volume, affects sleep-related snoring. The rs10878269 SNP, a G>A polymorphism, is associated with a reduced risk of snoring.
- Snoring is not a serious health concern unless linked to other sleep disorders like Obstructive Sleep Apnea(OSA).
- Changing your sleeping position, maintaining a healthy weight, reduced alcohol consumption and smoking, and throat exercises are some of the recommendations to have a snore-free sleep at night.
References
https://pubmed.ncbi.nlm.nih.gov/32060260/
Introduction: What is Sleep Bruxism?
Sleep Bruxism (also known as Teeth Grinding) is defined as repetitive jaw muscle activity during sleep. It is characterized by an unconscious act of grinding or clenching one's teeth tightly together. Over time, it could lead to damage of teeth, oral health conditions, facial muscle pain, sleep disturbances, difficulty while speaking or eating.
Sleep Bruxism is more common in children, adolescents, and young adults than middle-aged and older adults.
The prevalence of sleep bruxism is estimated to be around 15% in adolescents, around 8% of middle-aged adults, and only 3% in older adults.
According to statistical studies 6-50% of children experience nighttime teeth grinding.
How Does Genetics Influence Sleep Bruxism Risk?
Multiple studies have demonstrated that there may be a degree of inherited susceptibility to develop sleep bruxism. According to a study, around 21-50% of affected individuals have an immediate family member who had sleep bruxism during childhood.
Few studies have shown the significant associations of certain variants in neurotransmitters like dopamine, serotonin, and others ( DRD3, HTR2A, COMT, MMP9, and others) with sleep bruxism.
DRD3 Gene and Sleep Bruxism
The DRD3 gene encodes the D3 subtype of the dopamine receptor, which is localized to the regions of the brain involved in cognitive, emotional, and endocrine functions.
Variations in DRD3 are implicated in the physiopathology of diseases affecting those functions.
rs6280 and and Sleep Bruxism
The rs6280 is a T>C polymorphism located in the DRD3 gene, where the C allele may increase dopamine affinity and efficacy. Studies have shown that the Gly variant (C) is significantly associated with increased susceptibility to sleep bruxism.
Non-genetic Influences on Sleep Bruxism Risk
Sleep bruxism may be accelerated by lifestyle factors as well. Some of them include:
- Stress
- Alcohol consumption
- Anxiety
- Cigarette smoking
- Upper airway resistance
- Caffeine consumption
Effects of Bruxism on Health
- There is significant damage to the teeth. The teeth can become painful, shaky, and get eroded. Any implants have a risk of getting damaged.
- It leads to problems with the temporomandibular joint (TMJ) which connects the lower jaw to the skull. This causes locking of the jaw, difficulty with chewing, popping, or clicking noises, and chronic jaw pain.
- The sound from clenching and grinding your teeth can make it harder for the person you share your bed with to fall asleep.
Tips for Managing Bruxism
Mouth guards - Mouth guards help keep the teeth separated and hence prevent grinding.
Stress management - Stress is one of the major contributors to teeth grinding. So finding ways to alleviate stress can help prevent teeth grinding.
Avoid alcohol and caffeine - Teeth grinding tends to intensify upon alcohol and caffeine consumption.
Avoid chewing on pens and pencils - This practice gets your jaws used to grinding movement and may increase your tendency to grind your teeth.
Summary
- Sleep Bruxism is defined as repetitive jaw muscle activity during sleep. Over time, it could damage teeth, oral health conditions, facial muscle pain, sleep disturbances, and difficulty while speaking or eating.
- It is more common in children, adolescents, and young adults than in middle-aged and older adults.
- Few studies have shown the significant associations of certain variants in neurotransmitters like dopamine, serotonin, and others DRD3, HTR2A, COMT, MMP9, and others with sleep bruxism.
- The C allele of rs6280 SNP found in the DRD3 gene, a dopamine receptor, is associated with increased susceptibility to sleep bruxism.
- As sleep bruxism causes severe damage to the teeth over time and leads to problems with the temporomandibular joint, it needs to be managed. Using mouth guards, avoiding alcohol and caffeine, managing stress, and not chewing on pens and pencils can help.
References
https://pubmed.ncbi.nlm.nih.gov/32471213/
https://pubmed.ncbi.nlm.nih.gov/27611726/
https://pubmed.ncbi.nlm.nih.gov/28451935/
https://pubmed.ncbi.nlm.nih.gov/30092895/
https://pubmed.ncbi.nlm.nih.gov/25628080/
What is Sleep Fragmentation?
Sleep fragmentation is one of the symptoms of sleep disorders characterized by repeated, short sleep interruptions during the night, which leads to excessive tiredness during the day.
People with fragmented sleep tend to fall asleep quickly but wake up multiple times during the night for short periods. The other symptoms of fragmented sleep include morning headaches, daytime sleepiness, difficulty in concentrating, and memory lapses.
Fragmented sleep due to situational illness (like a cough or a sore back)is called short-term sleep fragmentation and goes away after some time.
Research studies have documented a greater impact on physical and emotional health when sleep quality and quantity are poor.
How Does Genetics Influence Sleep Fragmentation Risk?
A study reported the genetic and environmental variance in sleep complaints. The proportions were as follows:
1. At 8 years: 63% genetic, 32% non-shared environment
2. At 10 years: 66% genetic, 27% nonshared environment, 7% shared environment
The study also suggests that genetics affects sleep problems more strongly during the preschool/school age (63-69%) . Certain variants in HLA-DQB1, CRY1, and other genes might influence the risk of having fragmented sleep.
CRY1 and Sleep Fragmentation
The CRY1 gene encodes a protein called flavin adenine dinucleotide-binding, a key component of circadian clock regulation.
Variations in the CRY1 gene are found to be associated with altered sleep patterns.
rs184039278 and Sleep Fragmentation
The rs184039278 is an A>C gain of function mutation located in the CRY1 gene, associated with a prolonged period of circadian molecular rhythms.
A study, Patke, Alina, et al.2017, demonstrated that both CC and AC carriers are strongly associated with late sleep times and sleep fragmentation.
Non-genetic Factors That Influence The Fragmented Sleep Risk
Some sleep-related disorders can result in fragmented sleep. A few examples are:
1. Snoring
2. Obstructive sleep apnea
3. Sleep-maintenance insomnia
4. Restless leg syndrome
Poor sleep is also caused by lifestyle habits such as:
1. Alcohol and caffeine consumption
2. Napping for a long time in the day
3. Exercising close to bedtime
Effects of Sleep Fragmentation on Health
- Sleep fragmentation reduces the amount of sleep you get at night and leads to extreme fatigue during the day.
- It leads to a decrease in your concentration and productivity during the day.
- There is a risk of weight gain and mood-related disorders.
- It leads to increased stress and has a negative impact on your memory and cognitive function.
- Over a period of time, there is a risk of heart diseases, obesity, and diabetes.
- Behavioral problems in children are associated with sleep fragmentation.
Tips for Managing Sleep Fragmentation
You can follow these tips to have a peaceful night of sleep and avoid sleep fragmentation.
1. Tire yourself out: As fatigue accumulates throughout the day, it’ll be easier to fall asleep in the night.
2. Stay away from distractions: Switch off your phone, wear an eye mask, and shut the windows to prevent your sleep from being disturbed.
Summary
- Sleep fragmentation is characterized by repeated, short sleep interruptions during the night, which leads to excessive tiredness during the day. This has a great impact on physical and emotional health.
- The CRY1 gene encodes a protein called flavin adenine dinucleotide-binding, a key component of circadian clock regulation. The rs184039278 SNP found in this gene is associated with a prolonged period of circadian molecular rhythms, late sleep times, and sleep fragmentation.
- Snoring, OSA, RLS, and bad lifestyle habits can also lead to sleep fragmentation.
- Sleep fragmentation can lead to concentration, productivity, extreme fatigue, mood-related disorders, and other problems.
- Tiring yourself out and staying away from distractions can help avoid sleep fragmentation.
References
https://pubmed.ncbi.nlm.nih.gov/20975052/
https://pubmed.ncbi.nlm.nih.gov/28388406/
https://pubmed.ncbi.nlm.nih.gov/24179306/
What makes a person an early riser or a night owl?
Chronotype is influenced by differences in circadian rhythm, which refers to the fundamental 24-hour physiological cycle essential for various molecular and behavioral processes. It helps regulate sleep patterns.
The timing of circadian rhythms varies across individuals and is influenced by both environmental and genetic factors. People with earlier rhythms tend to rise early in the morning and feel sleepy earlier in the night. If your body sides with the “morning clock” then you are a “morning person.” The other end of this spectrum has people with delayed rhythms. They tend to sleep and wake up late and are often referred to as an “evening person” or a “night owl.”
Research has shown that morning people are more focused, persistent, agreeable, plan their future better, and are less likely to smoke and drink or get depressed. They may exhibit characteristics like:
- Waking up early
- Being more active during the morning hours
- Being more focused and happy
- Being more productive during the day
Similarly, night owls enjoy a burst of strength during the night and may exhibit characteristics like:
- Waking up late
- Being more active during the evening hours
- Being more creative and adventurous
- Being more productive during the night
How Does Genetics Influence Circadian Rhythm?
A GWAS study of self-reported chronotype (morning/evening person) of UK Biobank data identified 22 regions in the circadian rhythm and photo-reception genes associated with morningness. This was also replicated in a 23andMe study.
One of the strongest associations was seen in the rs516134 SNP located near the RGS16 gene.
RGS16 Gene and Circadian Rhythm
The RGS16 gene encodes a protein that belongs to the regulator of G protein signaling. This protein is responsible for turning off certain signal communications between cells in the body.
Microarray studies and gene expression analysis have demonstrated that the RGS16 gene exhibits circadian variations. According to a study, mice lacking this gene have a longer circadian period.
rs516134 SNP and Morningness
The rs516134 is a C>T polymorphism located in the RGS16 gene. The C allele is found to be strongly associated with morningness.
Non-genetic Influences On Circadian Rhythm
A study found that morningness is significantly associated with gender, with a prevalence of 39.7% in males and 48.4% in females.
Also, people over 60 were more likely to prefer mornings than people under 30 - meaning people’s sleep preferences may change over time.
Effects of Circadian Rhythms
Circadian rhythms affect day-to-day bodily functions such as sleep, eating habits, hormones release, and body temperature.
Many studies have documented that irregular rhythms are linked to various chronic conditions such as sleep disorders, obesity, depression, diabetes, hypertension, bipolar, and schizophrenia.
It is known that the vast majority of patients with depression have sleep abnormalities; either they sleep too much or have insomnia and can’t sleep at all.
Several genetic variants are correlated with how circadian rhythms function and their association with health conditions.
The interplay between genetics and non-genetic factors (such as sunlight, eating habits) with circadian rhythm is clear.
Maintaining a routine with a balanced lifestyle may help to stabilize the internal biological clock and health.
Tips To Become An Early Riser
- Sleep early and shift your bedtime gradually to get about 7-9 hours of sleep.
- Stay consistent with your timings. Set your alarm clock to the same time every morning to make it easier to get into a routine.
- Move your alarm clock to a distance where you would have to get up to turn it off. There are a few apps like Smart Alarm or Math Alarm which require you to do an activity to turn off the alarm. This will help you stay awake and not snooze your alarm and go back to sleep.
- Exposure to bright light in the morning, especially natural light, helps make you alert and gets you used to wake up early. Your body’s circadian rhythm is responsive to light and dark conditions.
- Get active in the morning and go for a jog or run. You can even hit the gym in the morning and finish your workout. This will give you the energy to start your day.
- Think about the various reasons why waking up in the morning could be beneficial and how you can be more productive during the day.
- Use something to look forward to in the morning as bait to wake up for. A cup of hot coffee, a nice breakfast, a puzzle in the newspaper are a few of the things that you could look forward to.
- A protein-heavy meal is said to increase your dopamine levels, facilitating wakefulness, and making you ready for the day.
Summary
- Circadian rhythm, which refers to the fundamental 24-hour physiological cycle essential for various molecular and behavioral processes, helps regulate your sleep patterns.
- People with earlier rhythms are termed as morning people, whereas those with delayed rhythms are termed as night owls. Morning people are known to be more focused and happy, while night owls are known to be more creative and adventurous.
- Both environmental and genetic factors influence your sleep patterns.
- Several genes are known to affect circadian rhythm. The C allele of the rs516134 SNP in the RGS16 gene, which is involved in turning off certain signals between cells in the body, is known to be strongly associated with morningness.
- Circadian rhythms affect your day-to-day functions, and irregularity is associated with chronic health conditions.
- Following a routine with a balanced and healthy lifestyle can help set your biological clock right.
References:
https://pubmed.ncbi.nlm.nih.gov/27494321/
https://pubmed.ncbi.nlm.nih.gov/26835600/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5428740/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4018537/
Introduction
Sleep is a critical component of optimal health. A healthy sleep comprises various aspects, including adequate duration, good quality, and the absence of sleep disorders. Inadequate sleep at night is generally associated with:
- Daytime sleepiness
- Daytime fatigue
- Depressed mood
- Poor functioning
- Other health issues
Sleep duration refers to the total amount of sleep obtained either during the nighttime sleep event or across the 24-hr period.
Importance of An Adequate Sleep
Getting enough sleep at night is very important for several reasons. Sleep is linked to your mental and physical health and quality of life. When you get adequate sleep at night, you can be more productive and concentrate better during the day. It reduces your risk of heart disease and prevents depression. Your immune system becomes stronger as sleep helps the body to repair and recover. Your athletic performance can also be improved because of a good night’s sleep. Not getting enough sleep can make you gain weight faster.
RDA: What Is The “Ideal” Sleep Duration?
National Sleep Foundation guidelines recommend 7-9 hours of sleep per night for healthy adults. Babies, young children, and teens need even more sleep to enable their growth and development. People over 65 should also get 7 to 8 hours of sleep per night.
How Does Genetics Affect Sleep Duration?
Studies have shown that certain genetic variants influence habitual sleep duration, which explains why some individuals need more sleep than others.
Twin studies have shown that the heritability estimation of sleep duration is around 10 - 40%.
A GWAS study of self-reported chronotype and sleep duration of UK Biobank data identified several genetic regions associated with sleep duration. This study documented that people with genetic variants for longer sleep duration reported an average of 22 minutes more sleep.
PAX8 Gene and Sleep Duration
The PAX8 gene encodes a member of the paired box (PAX) family of transcription factors involved in thyroid follicular cell development and the expression of thyroid-specific genes.
Variations in the PAX8 gene may affect different functions, including DNA binding, gene activation, and protein stability.
Research studies have found that the sleep-wake cycle may be influenced by regulating thyroid hormone levels. Individuals with hypothyroidism (a condition in which the thyroid gland does not produce enough thyroid hormones) are prone to excessive sleepiness. People with hyperthyroidism (in which the thyroid makes too much of the hormone), on the other hand, may have insomnia.
rs62158211 And Sleep Duration
The rs62158211 is a G>T polymorphism located in the PAX8 gene. The T allele is associated with longer sleep duration.
A study documented that the rs62158211 was associated with an average 2.6-minute per-allele change in sleep duration.
Non-genetic Influences On Sleep Duration
Some risk factors that lead to shorter sleep duration include alcohol consumption, smoking, and physical inactivity.
Effects of Sleep Duration on Health
Few epidemiological and genetic studies have demonstrated a strong biological link between abnormal sleep duration, risk of schizophrenia, type 2 diabetes, fetal growth, and Crohn's disease.
Sleep duration is also associated with cardiovascular diseases, type 2 diabetes, depression, automobile and workplace accidents, learning and memory problems, and prospective mortality.
TipsTo Become An Early Riser
- Sleep early and shift your bedtime gradually to get about 7-9 hours of sleep.
- Stay consistent with your timings. Set your alarm clock to the same time every morning to make it easier to get into a routine.
- Move your alarm clock to a distance where you would have to get up to turn it off. There are a few apps like Smart Alarm or Math Alarm which require you to do an activity to turn off the alarm. This will help you stay awake and not snooze your alarm and go back to sleep.
- Exposure to bright light in the morning, especially natural light, helps make you alert and gets you used to waking up early. Your body’s circadian rhythm is responsive to light and dark conditions.
- Get active in the morning and go for a jog or run. You can even hit the gym in the morning and finish your workout. This will give you the energy to start your day.
- Think about the various reasons why waking up in the morning could be beneficial and how you can be more productive during the day.
- Use something to look forward to in the morning as bait to wake up for. A cup of hot coffee, a nice breakfast, a puzzle in the newspaper are a few of the things that you could look forward to.
- A protein-heavy meal is said to increase your dopamine levels, facilitating wakefulness, and making you ready for the day.
Summary
- Sleep duration refers to the total amount of sleep obtained during the nighttime sleep event or across the 24-hr period. Getting enough sleep at night is necessary for both mental and physical well-being.
- For healthy adults, 7-9 hours of sleep is recommended. Babies, children, and teens tend to sleep for much longer.
- Genetics is found to influence sleep duration. The PAX8 gene, which plays a role in thyroid development, is associated with the sleep cycle. The regulation of thyroid hormone levels affects the sleep-wake cycle. The T allele of the rs62158211 SNP in this gene is associated with longer sleep duration.
- Certain risk factors like smoking, alcohol consumption, and physical inactivity lead to decreased sleep duration.
- Abnormal sleep duration is linked with the risk of schizophrenia, type 2 diabetes, fetal growth, and Crohn's disease.
- Exercising during the day, following a proper sleep routine, reducing alcohol consumption and smoking, a comfortable environment, and less frequent napping are some of the things that can make your sleep duration normal.
References:
https://www.sleepfoundation.org/articles/how-much-sleep-do-we-really-need
https://pubmed.ncbi.nlm.nih.gov/27992416/
https://pubmed.ncbi.nlm.nih.gov/27494321/
https://pubmed.ncbi.nlm.nih.gov/25469926/
Introduction: What Is Snoring?
Snoring is the loud or harsh sound from the nose or mouth that occurs when breathing is partially obstructed. The sound is produced when the soft palate and other soft tissues (such as uvula, tonsils, nasal turbinates, and others) in the upper airway vibrate.
Affecting nearly 90 million Americans, it can lead to disturbed, unrefreshing sleep, ultimately resulting in poor daytime function. Snoring is caused due to obstruction of air passage, resulting in the vibration of respiratory structures and the production of sound during breathing while asleep.
Snoring is more prevalent in males than in females. Certain risk factors such as genetic predisposition, throat weakness, obesity, mispositioned jaw, obstructive sleep apnea, sleep deprivation, alcohol consumption, and mouth breathing are associated with snoring.
How Does Genetics Influence Snoring Risk?
Twin and family studies have identified the association between genetic factors and snoring risk, with heritability ranging between 18 to 28%.
A recent study published in 2019 leveraged data from a large U.K. Biobank study consisting of the Australian adult population to identify the molecular mechanisms associated with snoring.
MSRB3 Gene and Snoring
MSRB3 is associated with protein and lipid metabolism pathways, which are related to hippocampal volume (a region in the brain) and lung function. Such genetic associations are consistent with the findings that severe bouts of snoring may be due to:
- Nocturnal oxygen desaturation (temporary drop in oxygen levels in hemoglobin)
- Lowered neuropsychological functions, with reduced ability to consolidate memory.
rs10878269 And Snoring
The rs10878269 is G>A polymorphism located in the MSRB3 gene. A study by Jones, Samuel E., et al.2016 showed that variant rs10878269 was significantly associated with reduced snoring risk.
Non-genetic Influences On Snoring
- Mouth anatomy* : A low, thick, and soft palate can narrow down the airway and may result in snoring
- Nasal problems : Deviated nasal septum and nasal congestion can contribute to snoring.
- Sex : Men are more likely to snore or have sleep apnea than women.
- Obesity : Fatty tissues in the neck of obese/overweight people can narrow the airways and cause snoring.
- Sleep Deprivation : Not getting enough sleep can lead to throat relaxation.
Effects Of Snoring
Snoring is not often considered a serious health concern except in some conditions. Snoring can usually be cured through simple home remedies. Light and infrequent snoring is completely normal. Snoring that is linked to obstructive sleep apnea (OSA) is, however, worrisome and needs to be treated.
Tips For A Snore-free Sleep
- Reduce the consumption of alcohol and sedatives as this relaxes your muscles and leads to snoring.
- Maintain your weight as obesity and being overweight are risk factors for snoring and sleep apnea.
- Change your sleeping position. When you sleep on your back, your airway has higher chances of getting blocked. Sleeping on your side, raising your head by a few inches, or using a pillow to improve your neck position are a few alternative sleep positions to try.
- Relieve nasal congestion before you sleep.
- Anti-snoring mouthpieces can be used to hold your jaw and tongue in a suitable position to prevent blockage of the airway,
- Throat exercises can help strengthen the muscles and prevent them from collapsing during sleep.
- Try to quit smoking. Smoking can result in inflammation in the upper airway passage, and this blocks airflow.
Summary
- Snoring is a common sleep disorder that affects over 90 million Americans. It is characterized by a loud noise from the nose/mouth due to an obstructed airway.
- Genetic predisposition, throat weakness, obesity, mispositioned jaw, obstructive sleep apnea, sleep deprivation, alcohol consumption, and mouth breathing are some risk factors associated with snoring.
- The MSRB3 gene, associated with protein and lipid metabolism pathways related to lung function and hippocampal volume, affects sleep-related snoring. The rs10878269 SNP, a G>A polymorphism, is associated with a reduced risk of snoring.
- Snoring is not a serious health concern unless linked to other sleep disorders like Obstructive Sleep Apnea(OSA).
- Changing your sleeping position, maintaining a healthy weight, reduced alcohol consumption and smoking, and throat exercises are some of the recommendations to have a snore-free sleep at night.
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