In this study, researchers sampled genetic markers in the blood of volunteers who’d experienced seven days of reduced sleep time. After a 10 day interval, the volunteers then returned to the lab, and the RNA was sampled again after they had seven nights of sleep for at least eight and a half hours.
The connection with health and disease
The scientists noticed that reduced sleep time changed how hundreds of genes were expressed in the body, which is an indicator cell function and of our health. Insufficient sleep raises levels of oxidative stress, which damages our genes, and how they express themselves. When exposed to chronic oxidative stress, our cellular genes may become damaged and express themselves by creating mutated cells. Cellular mutations caused by oxidative stress can lead to cancer and other health conditions.
Getting optimal amounts of sleep therefore is an essential component of reducing your risk of developing diseases that impair your quality of life and may limit what you can do. The health conditions arising from sleeping too little also gradually drain your bank account when you have to pay for doctors fees, medications, and inflated health insurance premiums.
Prior research has identified that getting less than six hours of sleep each night is associated with hastening all causes of death (2), obesity (3), diabetes (4), cardiovascular disease (5), and impaired vigilance (alertness) and cognition (6). You also damage your brain and liver when you get insufficient sleep (7). The need for more sleep is widespread throughout the United States; according to the Centers for Disease Control and Prevention, 30% of civilian adults in the United States (approximately 40.6 million workers) report an average sleep duration of 6 h or less (8).
What the researchers did
Twenty six human participants (12 women and 14 men) slept in a research center for 5.7 hours for seven consecutive nights. Each was apparently healthy, and 19 of the 26 volunteers were white / caucasian in origin. Their average age was 27.
Ten RNA samples were then taken from each participant’s blood at three-hourly intervals after they’d slept for 5.7 hrs p/night for a week. RNA is a collection of different types of molecules that help to compile your genes. Your genes then act like the instruction set - the programming - that tells your cells what to do, how to behave, and how to reproduce themselves.
In this study, the researchers sampled the RNA from the participants‘ blood. Your blood stream contains many different types of RNA, and by sampling the blood, and identifying what types of RNA were present, the researchers were able to identify what types of biological processes were happening inside the participants bodies. The three-hourly blood-draw internals spanned just over a day, and participants were awake for the 30 hours. As a health coach, I do wonder whether keeping people awake for 30 hours was unhealthy for them, and may also have affected the levels of RNA in the blood.
The volunteers then had at least a 10-day break between the next part of the study, in which they slept for 8.5 hours per night for seven consecutive nights. Ten ribonucleic acid (RNA) samples were again extracted from each participant’s blood every three hours. Each of the participants’ two visits to the sleep lab lasted 12 days, to help them acclimatize to the lab, learn the lab procedures needed to evaluate their reaction times and sleepiness, and to get into a regular sleeping rhythm before and after each leg of the trial.
The RNA samples in the participants blood were analyzed, and the results revealed that insufficient sleep for as little as one week impacted the following bodily systems:
- Chromatin modification (how our cells’ nucleus is altered)
- Gene-expression regulation
- Macro-molecular metabolism (affecting nutrient uptake, and energy levels)
- Inflammatory responses increased
- Immunity adversely affected
- Stress responses impaired
Take home message
Sleeping at night is needed to keep your skin young looking, to keep your energy levels high, to repair your muscles after exercise, to allow your immune system to work effectively, and to psychologically integrate and process the events of the previous day. Your function more effectively, and are a far happier and more energetic person when you have at least 8.5 hours of sleep each night. Turn the lights out by 10.30pm (by 10pm if you’re chronically sleep deprived) and get up after 6am or preferably around sun rise.
(1) Moller-levet et al. (2013). Effects of insufficient sleep on circadian rhythmicity and expression amplitude of the human blood transcriptome. Proceedings of the National Academy of Science Plus, doi/10.1073/pnas.1217154110
(2)Cappuccio FP, D’Elia L, Strazzullo P, Miller MA (2010) Sleep duration and all- cause mortality: A systematic review and meta-analysis of prospective studies. Sleep 33(5):585–592.
(3) Nielsen LS, Danielsen KV, Sørensen TI (2011) Short sleep duration as a possible cause of obesity: Critical analysis of the epidemiological evidence. Obes Rev 12(2): 78–92.
(4) Knutson KL (2010) Sleep duration and cardiometabolic risk: A review of the epidemiologic evidence. Best Pract Res Clin Endocrinol Metab 24(5):731–743.
(5) Cappuccio FP, Cooper D, D’Elia L, Strazzullo P, Miller MA (2011) Sleep duration predicts cardiovascular outcomes: A systematic review and meta-analysis of prospective studies. Eur Heart J 32(12):1484–1492.
(6) Kronholm E, et al. (2011) Psychomotor slowness is associated with self-reported sleep duration among the general population. J Sleep Res 20(2):288–297.
(7) Maret S, et al. (2007) Homer1a is a core brain molecular correlate of sleep loss. Proc Natl Acad Sci USA 104(50):20090–20095.
(8) Centers for Disease Control and Prevention (CDC) (2012) Short sleep duration among workers—United States, 2010. MMWR Morb Mortal Wkly Rep 61(16):281–285.