Scientists try to identify the genetic causes of poor sleep by using data from Fitbit-like devices and genome analysis.
We have all been there—skipping out on sleep because of something important. Whether we need to meet a deadline, cram for exams, or feed the baby, we power through the night even though we know we will suffer for it the next day. When those situations arrive, the very last thing on our mind is what the lack of sleep does to our body. It may be shocking to know the full extent to which poor sleep affects our health.
Sleep deprivation and its effects on the body
Sleep is essential to a healthy lifestyle in much the same way as good nutrition and exercise. In contrast to what people may think, the brain is highly active during sleep. When we sleep, we process the information we received during the day and consolidate memory.
However, the main biological function of sleep remains a mystery. Sleep has far-reaching effects on numerous tissues within the body, for example, heart rate and breathing stability. There is evidence to suggest that lack of sleep can increase the risks of getting cancer, high blood pressure, cardiovascular disease, diabetes, and obesity.
Sleep deprivation also has a negative impact on our immune system and affects how resistant we are to infectious disease. Poor sleep can reduce cognitive and motor function to the same extent as alcohol consumption. Inadequate sleep is also strongly associated with psychiatric disorders such as depression, anxiety and dementia. It is clear that sleep is essential for staying healthy but what causes poor sleep?
What causes poor sleep?
There are two biological mechanisms that regulate our sleeping pattern: sleep homeostasis and circadian rhythms. Sleep homeostasis is the body’s need for sleep, the longer you are awake the more you need to sleep.
Circadian rhythms control the timing of when you sleep, they process the environmental queues that make you sleepy such as light. Circadian rhythms affect a large number of biological process from body temperature to hormone regulation.
Sleeping patterns are coded in our genes
Both these biological mechanisms are regulated by our genes. As a result, our sleeping patterns are hereditary. Studies conducted in twins and family groups have shown that sleeping patterns ranging from sleep duration and excessive sleepiness are inherited.
There is even evidence to suggest preferences for morning or evening wakefulness (morning people or night owls) and prolonged sleep latency (difficulty falling asleep) is heritable. The exact mechanisms that regulate the quality, quantity and timing of sleep are still unknown.
Scientists use Fitbit data to identify good sleep traits
In a recent study published in Nature Communications, an international group of researchers wanted to know if they could isolate genes associated with healthy sleeping patterns.
The group used data from 85,670 UK Biobank participants. The researchers used data gathered from accelerometers, which are devices that are similar to a Fitbit. They are worn on the wrist and detect rest/activity cycles of the participant. The accelerometers were worn for a period of seven days.
Genetic analysis reveals genes associated with good sleeping habits
The biobank participants also gave samples that allowed the scientists’ to analyses the entire genetic makeup (genome) of each person. The researchers performed a genome-wide association study. They identified 8 sleep traits that were representative of sleep quality, quantity and timing from the accelerometer data.
The group then looked at all the genes in each participant and used statistical analysis to identify if there were any versions of the genes that were associated with these sleeping traits. The researchers were able to identify 47 genetic associations across seven of the traits. They found 10 new genetic variations that were associated with sleep duration and 26 new variants associated with sleep quality.
The variations were found in genes that were mainly involved in the serotonin pathway which is not surprising as serotonin is well known for its role in regulating sleep cycles. High levels of serotonin are linked to wakefulness while low levels correspond to sleep.
Study limitations
Although this study showed promising results there were a few limitations to keep in mind when analyzing the data. The participants in the UK Biobank are not representative of the entire UK populations due to their high socioeconomic status and they are on average healthier than the general population. The accelerometers cannot distinguish the difference between awake and not moving, and sleeping. This makes interpreting the data difficult. While there are limitations to the work presented by this group the insights offered by this study lay the groundwork for further investigation.
Foundations for future analysis
The genes variations identified in this study will form the foundation for future work uncovering the molecular biology that regulates our sleeping patterns. These discoveries may allow for the development of new therapies and diagnostic technologies to help improve sleeping habits and general health.
In a press release, lead author Dr. Samuel Jones said, “This study is part of an emerging body of work which could one day inform the development of new treatments to improve our sleep and our overall health.”
Written by Tarryn Bourhill, MSc, PhD Candidate
References
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- Fernandez-Mendoza, J. & Vgontzas, A. N. Insomnia and its Impact on Physical and Mental Health. Current Psychiatry Reports 15, 418, doi:10.1007/s11920-013-0418-8 (2013).
- Jones, S. E. et al. Genetic studies of accelerometer-based sleep measures yield new insights into human sleep behaviour. Nature Communications 10, 1585 (2019).
- Vennells, L. Research identifies genetic causes of poor sleep <https://www.eurekalert.org/pub_releases/2019-04/uoe-rig040419.php> (2019).
