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

Abstract

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.

The Link Between Sleep And Mood

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.

Waking just one hour earlier cuts depression risk by 23%

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. 

Recommendations to become an early riser

• Practice going to bed early. Research suggests that an early bedtime improves academic performance and cognitive thinking.
• Start waking up a little earlier than you did the day before. Studies have linked early risers to  increased physical activity and improved attention.
• Motivate yourself to wake up early with a planned schedule. Studies have reported an association between the motivational state of mind and the sleep cycle of an individual.
• Reward yourself when you wake up early. Studies have linked the reward system to learning behavior and improved wellness. 

Summary

• Depression, a mood disorder characterized by feelings of sadness, is usually linked to lack of sleep and other factors like family history, stress, etc.
• Previous studies indicate a link between sleep timing and mood. Further research on this revealed that night owls are more likely to suffer from depression than early birds.
• A genetic study was conducted on 850,000 individuals to understand the causal relationship between sleep schedule and depressive disorders.
• Researchers identified around 340 common genetic variants which influence an individual’s sleep preference and time.
• Findings of the study suggest that waking up an hour earlier reduces your risk of depression by 23%.

References

• https://www.sciencedaily.com/releases/2021/05/210528114107.htm
• https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2780428
• https://www.healthline.com/health/depression
• https://www.webmd.com/depression/sleep-depression
• https://healthysleep.med.harvard.edu/need-sleep/whats-in-it-for-you/mood
• https://jackheimbigner.medium.com/how-to-become-an-early-riser-in-5-simple-steps-41c3904e5b1f
• https://jackheimbigner.medium.com/how-to-become-an-early-riser-in-5-simple-steps-41c3904e5b1f