Insufficient sleep is related to a range of health problems, from diabetes and cardiovascular disease to depression, poor immune function, and cognitive decline, particularly in later years. For all that we know about the health risks associated with lack of sleep, we actually don't know a lot about exactly how poor sleep contributes to poor health. The mechanics of the relationship between sleep and disease remain little understood.
New research may offer some important insight into how sleep affects heath. A new study indicates that poor sleep can significantly disrupt and inhibit normal gene activity in hundreds of genes. The genes affected help to govern broad and important biological functions, including stress, the immune system, inflammation, metabolism, and circadian rhythms. A team of researchers led by scientists at England's University of Surrey examined the influence of sleep on gene function and found that a week of low sleep altered the activity of more than 700 genes. The study was collaborative effort among specialists in sleep science, genomics, physiology, and bioinformatics.
The study included 26 adults whose sleep was monitored for two weeks. During the first week, participants sleep slightly fewer than six hours per night, less than the recommended seven to eight hours. During the second week, they slept 8.5 hours nightly. After the conclusion of each week, researchers took blood samples and analyzed them to identify any changes in genetic activity. After controlling for other factors, including exposure to light, activity levels, and food, the results showed that a single week of insufficient sleep had a dramatic effect on gene activity:
- Low sleep altered the activity of 711 genes.
- The total number of genes affected by sleep increased by seven times after one week of sleep deprivation.
- Many of our genes rise and fall in activity in accordance with our body's 24-hour circadian clock. A week of insufficient sleep reduced the total number of genes that rise and fall in line with circadian rhythms from 1,855 to 1,481.
- Sleep deprivation also diminished the amplitude of the rise and fall of some of these circadian-aligned genes.
The genes affected by sleep deprivation help govern circadian rhythms, metabolic functions, and sleep homeostasis -- the regulation of sleep itself. These are genes connected to immune system functioning, inflammation levels, and stress responses. Previous research has shown that disrupted sleep is indeed strongly associated with health problems related to these biological functions:
Circadian rhythms. In recent years, we've learned a great deal about the importance of our circadian rhythms to health. Sleep itself is one of the many essential biological functions governed by our 24-hour circadian clock. Disruptions to circadian function are associated with a range of health problems, including psychiatric disorders, dementia, metabolic disorders such as diabetes, autoimmune disorders such as rheumatoid arthritis, and cancer.
Metabolism. Disrupted sleep is also strongly associated with metabolic diseases, including obesity, metabolic syndrome, and diabetes. Studies have shown that sleep problems can predict the future development of metabolic syndrome, a disorder that is associated with higher risk for diabetes and cardiovascular disease. Sleep is a critical factor in healthy weight control, and sleep deprivation is strongly linked to obesity. And there is a great deal of research to indicate that poor sleep increases the risk of diabetes, perhaps by contributing to insulin resistance.
Inflammation. Inflammation in the body is linked to a long list of health problems, including cardiovascular disease, chronic pain, diabetes, and cancer. Insufficient sleep has been linked to an increase in inflammation. This study showed people who slept six or fewer hours per night had higher levels of inflammation than those who slept between six and nine hours nightly.
Immune system. Research has also shown that sleep plays a role in immune system functioning. Numerous studies in recent years indicate that disrupted sleep, as well as too little sleep, may compromise healthy immune activity. This recent research found poor sleep to be as damaging to the immune system as stress.
Stress. Stress response is another biological process affected by the gene disruption found in this latest study. The relationship between sleep and stress is complicated. Stress can interfere with both the quantity and quality of sleep, as this study shows. And insufficient sleep can have negative effects on the way we respond to stress. Research shows that low sleep is linked to hormonal changes that can affect stress response. Studies also show that healthy sleep works to ease the emotional sting of difficult memories. Lack of sleep may inhibit our ability to process difficult emotional experiences, prolonging periods of stress and anxiety.
There's an abundance of scientific evidence linking sleep to these and other health problems. But we're just scratching the surface of understanding the underlying pathways by which sleep influences health. Understanding more about how sleep affects genetic function holds great promise in illuminating these pathways and could open important new avenues for both treatment and prevention of illness and disease.
Michael J. Breus, Ph.D.
The Sleep Doctor™
Everything you do, you do better with a good night's sleep™
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