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In the era of nutritional and wellbeing awareness, it's no secret that all the processes of the body are interconnected.
Experts up till now have identified strong evidence to suggest that eating habits are crucial for the quality of sleep.
But what about the other way round?
Could your sleep quality, duration, and hygiene affect how much you eat?
The hunger hormone found in our body is called Ghrelin.
Its main function is to increase our appetite and induce the feeling of hunger.
Ghrelin also regulates glucose homeostasis (blood sugar regulation) and promotes fat storage.
On the other hand, a hormone called Leptin induces satiety or the feeling of fullness.
The levels of both these hormones significantly influence your eating habits.
Image: Hunger-regulating hormones
Research has shown that sleep patterns influence ghrelin levels.
When a person is asleep, the body reassures the brain that the existing energy levels are sufficient for the time being.
Hence, the ghrelin levels decrease, and at the same time, leptin levels rise.
A study has found a significant association between sleep duration and leptin and ghrelin levels, independent of age, sex, BMI, and other confounding factors.
A single night of disrupted sleep increases ghrelin levels and typically has no effects on leptin levels.
However, chronic sleeplessness results in the fall of leptin levels as well.
According to a report in the journal of the Public Library of Science, those who consistently slept for 5 or less hours a night had a significantly different profile of the hunger hormones than those who consistently slept for 8 hours.
These changes in the hormone levels ultimately lead to increased hunger and excessive eating, all of which may result in weight gain and obesity.
A randomized clinical trial was conducted to examine the effects of sleep extension on energy intake among overweight adults.
The results, published in JAMA Internal Medicine on the 7th of February, reported that the participants who slept for an extra 1.2 hours (72 minutes) per night reduced their energy consumption by 270 kcals per day.
| No. of participants | 80 adult men and women |
| Age | 21-40 years |
| BMI (Body Mass Index) | 25.0-29.9 |
| Mean sleep duration | 6.5 hours |
| Race | Asian, Black or African American, Hispanic, and White |
The participants used an accelerometer-based monitor with an event marker to record their sleep-wake patterns.
During the 2-week baseline, the participants followed their habitual sleep duration.
At the end of two weeks, the participants chosen for sleep extension underwent a counseling session with a sleep hygienist.
The study investigators then advised this group of participants to extend their sleep duration to 8.5 hours.
On day 22, the participants returned for a brief follow-up and counseling session (if required).
The energy intake and storage were measured using the doubly labeled water method, a urine-based test.
Sleep is a vital part of maintaining a healthy lifestyle and preventing a plethora of diseases.
Those who habitually sleep for seven hours or less can benefit in terms of weight loss when they extend their sleep duration.
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.
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 :
Learn Your Genetic Risk for Atrial Fibrillation with Xcode Life’s Gene Health Report
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 included 286,353 people who were in paid employment or self-employed.
The study cohort was divided into:
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:
The study further revealed two more interesting findings.
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.
The common ingredient in your tea, coffee, and energy drinks, caffeine, is the strongest psychoactive drug in the world. It is not a secret that caffeine helps you stay awake. But, how does it manage to do that?
Let's first look at how your brain puts you to sleep.
Adenosine triphosphate, or ATP, is the energy currency of your body. ATP is broken down into a molecule called adenosine in the brain. Adenosine moves around the neurons keeping up your energy levels throughout the day.
As the day progresses, some of these adenosine molecules exit the neurons and bind to the receptors. This causes sleepiness. There are two adenosine receptors, A1 and A2A. A1 receptors are found on neurons that keep the brain awake, and A2A receptors are found on neurons that initiate sleep.
Image: Adenosine receptors and sleep
When adenosine binds to the A1 receptor, it reduces the activity of the neurons. When it binds to the A2A receptors, it increases the activity of the receptor. The combination of this binding, along with a few other hormonal changes, makes you sleepy. When you sleep, the adenosine is slowly released from the receptors, and when there isn't enough left to bind to the receptors, you wake up from a refreshed night of sleep.
Caffeine and adenosine are similar in structure. So, the caffeine can mimic the adenosine molecules and bind to the A1 and A2A receptors. However, caffeine's structure isn't identical to adenosine. As a result, it doesn't produce the "sleepy" effect.
Instead, it wards off sleepiness by preventing the adenosine molecules from binding and initiating the sleep process.
Image: Caffeine binding to adenosine receptors
But this effect lasts for only two to four hours, depending on how fast your body can break down the caffeine. This largely depends on your genes. When your body starts getting used to the caffeine intake, it produces more adenosine receptors to counteract the effect of caffeine. You may have to end up consuming more caffeine to stay awake!
Increased caffeine consumption leads to increased production of the receptor, which again results in increased caffeine consumption. It is a pretty vicious cycle that can make you a chronic caffeine drinker! As a result, you eventually develop caffeine tolerance. When you abruptly bid farewell to caffeine, you may end up feeling way too drowsy because of the additional adenosine receptors in the brain. This is called caffeine withdrawal.
Caffeine withdrawal is characterized by other symptoms like:
They can last up to a week till the number of receptors goes back to normal. Caffeine isn't as addicting or life-threatening compared to drugs like cocaine. People tend to have a mild physical dependence on this drug. People cannot overdose on caffeine easily. An average adult would have to have about 100 cups of coffee, which amounts to 10 grams of caffeine, to experience any lethal effects of caffeine.
The adenosine receptors are also found in the heart and kidneys. Activation of the receptors decreases the activity of these organs as well. Reduced urine output and heart rate prepare the body for a good night's sleep. However, when caffeine goes and binds instead, it results in increased heart rate and urine production. This is manifested as caffeine jitters and dehydration.
Caffeine isn't very dangerous; however, children should avoid it. Scientists haven't understood the effect of caffeine on a developing brain yet. It is also unhealthy for an adult to be consuming too much caffeine. Sleep and rest are essential for healthy brain function and well-being.
The genes that metabolize caffeine can say a lot about how much caffeine is "healthy" for you. A genetic test can help identify your caffeine metabolizing status.
Xcode Life's Gene Sleep report profiles genes that influence sleep upon caffeine consumption. All you need is your genetic ancestry test raw data to get started!
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 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.
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.
The common ingredient in your tea, coffee, and energy drinks, caffeine, is the strongest psychoactive drug in the world. It is not a secret that caffeine helps you stay awake. But, how does it manage to do that?
Let's first look at how your brain puts you to sleep.
Adenosine triphosphate, or ATP, is the energy currency of your body. ATP is broken down into a molecule called adenosine in the brain. Adenosine moves around the neurons keeping up your energy levels throughout the day.
As the day progresses, some of these adenosine molecules exit the neurons and bind to the receptors. This causes sleepiness. There are two adenosine receptors, A1 and A2A. A1 receptors are found on neurons that keep the brain awake, and A2A receptors are found on neurons that initiate sleep.
When adenosine binds to the A1 receptor, it reduces the activity of the neurons. When it binds to the A2A receptors, it increases the activity of the receptor. The combination of this binding, along with a few other hormonal changes, makes you sleepy. When you sleep, the adenosine is slowly released from the receptors, and when there isn't enough left to bind to the receptors, you wake up from a refreshed night of sleep.
Caffeine and adenosine are similar in structure. So, the caffeine can mimic the adenosine molecules and bind to the A1 and A2A receptors. However, caffeine's structure isn't identical to adenosine. As a result, it doesn't produce the "sleepy" effect.
Instead, it wards off sleepiness by preventing the adenosine molecules from binding and initiating the sleep process.
But this effect lasts for only two to four hours, depending on how fast your body can break down the caffeine. This largely depends on your genes. When your body starts getting used to the caffeine intake, it produces more adenosine receptors to counteract the effect of caffeine. You may have to end up consuming more caffeine to stay awake!
Increased caffeine consumption leads to increased production of the receptor, which again results in increased caffeine consumption. It is a pretty vicious cycle that can make you a chronic caffeine drinker! As a result, you eventually develop caffeine tolerance. When you abruptly bid farewell to caffeine, you may end up feeling way too drowsy because of the additional adenosine receptors in the brain. This is called caffeine withdrawal.
Caffeine withdrawal is characterized by other symptoms like:
They can last up to a week till the number of receptors goes back to normal. Caffeine isn't as addicting or life-threatening compared to drugs like cocaine. People tend to have a mild physical dependence on this drug. People cannot overdose on caffeine easily. An average adult would have to have about 100 cups of coffee, which amounts to 10 grams of caffeine, to experience any lethal effects of caffeine.
The adenosine receptors are also found in the heart and kidneys. Activation of the receptors decreases the activity of these organs as well. Reduced urine output and heart rate prepare the body for a good night's sleep. However, when caffeine goes and binds instead, it results in increased heart rate and urine production. This is manifested as caffeine jitters and dehydration.
Caffeine isn't very dangerous; however, children should avoid it. Scientists haven't understood the effect of caffeine on a developing brain yet. It is also unhealthy for an adult to be consuming too much caffeine. Sleep and rest are essential for healthy brain function and well-being.
The genes that metabolize caffeine can say a lot about how much caffeine is "healthy" for you. A genetic test can help identify your caffeine metabolizing status.
Xcode Life's Gene Sleep report profiles genes that influence sleep upon caffeine consumption. All you need is your genetic ancestry test raw data to get started!
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.
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 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.
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.
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.
https://pubmed.ncbi.nlm.nih.gov/32060260/
Depression, a fairly common mood disorder, is a major influencer of health and wellness. Recent research has found a link between depression and sleep timing and preferences. The reports suggest that an individual who wakes up an hour earlier than usual has a significantly decreased depression risk. These results could help a person improve their mental health by fixing their sleep cycle.
Depression is characterized by feelings of loss, sadness, and anger. Such mood disorders are usually linked to lack of sleep and various other factors like stress, family history, etc.
Previous studies have found an association between sleep timing and mood. Further insights from these studies have shown that night owls are twice as likely to suffer from depression as early risers regardless of their sleep duration.
Another study showed that early risers were up to 27% less likely to develop depression over the years. But, additional research is needed to examine the genetic and environmental factors and understand the relationship between sleep and mood disorders.
12-24% of our sleep timing is influenced by genetics. Researchers have found over 340 genetic changes that play a role in a person’s chronotype - morning or evening person.
Mood disorders can disrupt sleep cycles; hence researchers have been working on finding a causal relationship between them. These findings could hold significant implications for improving mental health.
A genetic study led by Iyas Daghlas M.D aimed to understand the protective nature of sleep schedule shifts.
The study was conducted with data of up to 850,000 individuals from UK-based Biobank and DNA testing company 23andMe - 85,000 who had worn wearable sleep trackers for seven days and 250,000 who had filled out sleep-preference questionnaires.
A third of this group self-identified as morning larks, and only 9% were night owls; the rest were somewhere in the middle.
The study also used a different sample consisting of genetic information along with surveys about diagnoses of major depressive disorders and anonymized medical and prescription records.
The results of the study suggest that scheduling your sleep an hour early can reduce your risk of major depressive disorder by 23%. Further, going to bed 2 hours early can cut down the risk by 40%!
The study also lays down a possible explanation that could explain this result. Going to bed early makes it easier to wake up early in the day. This could mean longer exposure to the daylight, which has a positive impact on mood. Others seem to suggest that having a biological clock that differs from most people can itself be depressing.
Caffeine is a central nervous system stimulant, which is widely used for its psychoactive effects. It is commonly used to alleviate behavioral, cognitive, and emotional deficits caused by sleep deprivation.
Regardless of its beneficial effects, caffeine may have adverse sleep-related consequences that might lead to sleep disruption and insomnia symptoms. This is because caffeine consumption is associated with lower levels of 6-sulfatoxymelatonin. 6-sulfatoxymelatonin is a substance produced during the metabolism of melatonin. It is involved in the regulation of circadian rhythm. Lower levels of 6-sulfatoxymelatonin can result in increased alertness (wakefulness).
CYP1A2 encodes cytochrome P-450 group of enzymes. These enzymes influence the absorption and metabolization of caffeine. Caffeine is absorbed rapidly and completely from the gastrointestinal tract. After absorption, the P-450 enzymes help with the metabolization. Variation in the CYP1A2 activity represents a major source of variability in the pharmacokinetics (drug absorption, distribution, metabolism, and excretion) of caffeine.
While the CYP1A2 gene is responsible for caffeine metabolism, another gene, ADORA2A, influences how your sleep is affected by caffeine intake. This gene encodes the adenosine receptor. When an adenosine molecule binds to this receptor, it inhibits all the processes that are associated with wakefulness. Caffeine acts as an adenosine receptor antagonist - it mimics adenosine and goes and binds to the adenosine receptor. This results in increased levels of free adenosine, leading to a boost in neuronal activity and wakefulness.
The adenosine A2A receptor (ADORA2A receptor) plays a role in the effects of caffeine on arousal. Mice lacking functional A2A receptors do not show increased wakefulness in response to caffeine administration, indicating that the A2A receptor mediates the arousal response.
The rs5751876 is a T>C polymorphism located in the ADORA2A gene, which modulates the sleep-wake cycle, and contributes to individual sensitivity to caffeine effects on sleep.
Studies have documented that in caffeine consumers (less than 300mg), rs5751876 - T allele is associated with a decreased risk of sleep complaints and insomnia as compared to the C allele.
If caffeine consumption is not wisely regulated, it could lead to delayed sleep and sleep deprivation. Sleep deprivation is associated with lapses in attention, lowered alertness, and reduction in cognitive function. Scientific studies have shown that a reduction in sleep time of 90 minutes could reduce objective alertness during the day time by one-third.
https://pubmed.ncbi.nlm.nih.gov/31817803/
https://pubmed.ncbi.nlm.nih.gov/15965471/
Obstructive Sleep Apnea (OSA) is a common, serious, and potentially life-threatening sleep disorder. It is characterized by frequent episodes of partial or complete upper airway obstruction during sleep.
This results in intermittent hypoxemia (low level of oxygen in the blood) and arousal.
Here, the throat muscles relax at irregular intervals and fail to keep the airway open. This results in inadequate breathing for 10 seconds or longer. Thus, the oxygen levels lower, and carbon dioxide levels build up. The brain interprets this as a need to open the airway and wakes you up in the process. This awakening is usually too brief to be remembered. A very noticeable sign of OSA is snoring.
More than 18 million American adults have been estimated to have sleep apnea.
How Does Genetics Influence the Risk of Obstructive Sleep Apnea?
Genes thought to be associated with the development of obstructive sleep apnea are involved in many body processes. They include:
- Communication between nerve cells
- Breathing regulation
- Control of inflammatory responses by the immune system
- Development of tissues in the head and face (craniofacial development)
- The sleep-wake cycle
- Appetite control
African-Americans and Pacific Islanders have more genetic variants associated with sleep apnea than Europeans. Variations in genes such as TNF, CRP, PLEK, PTGER3, LPAR1, HTR2A, and GDNF are associated with the risk of obstructive sleep apnea. Studies suggest that variations in multiple genes, each with a small effect, combine to increase the risk of developing the condition.
The TNFA gene encodes a proinflammatory cytokine (a molecule released by the T-immune cells) that belongs to the tumor necrosis factor (TNF) superfamily. It regulates various biological processes, including cell proliferation, differentiation, apoptosis, lipid metabolism, and coagulation. Studies have shown that TNF is involved in the regulation of sleep by influencing the adenosine receptor expression.
The rs1800629 is G>A polymorphism located in the TNFA gene associated with increased transcriptional activity and higher TNF levels. This SNP has been studied to contribute to the pathogenesis of sleep disorders. Studies have shown that the rs1800629 - A allele carriers are associated with an increased risk of developing obstructive sleep apnea when compared to G allele carriers.
Non-genetic Influences On OSA Risk
Some non-genetic risk factors for OSA are:
- Narrowed airway
- Smoking
- Hypertension
- Obesity
- Gender
- Menopause
- Diabetes
According to a 2013 study, people with type 2 diabetes have nearly a 50% chance of being diagnosed with OSA. Both of these often coexist because of shared risk factors.
Effects Of OSA on Health
Some effects of OSA that could interfere with everyday functioning include:
- Difficulty in concentrating
- Excessive daytime sleepiness
- Irritability, sexual dysfunction
- Nighttime sweating
- Learning and memory difficulties
Tips for Managing Obstructive Sleep Apnea
Summary
References
https://pubmed.ncbi.nlm.nih.gov/22043116/
https://pubmed.ncbi.nlm.nih.gov/23155414/
https://pubmed.ncbi.nlm.nih.gov/20538960/
