The Science of Sleep

  • Published
  • By Guy Leahy
  • Health Promotion Flight

The more we learn about sleep, the more we realize how important it is to overall health.

Sleep deprivation has economic effects; a recent study concluded that lack of sleep costs the U.S. economy up to $411 billion per year in low work productivity and mortality. According to the report, the U.S. loses just over 1.2 million working days per year due to sleep deprivation. The report also found that a person who sleeps less than six hours a night has a 13 percent higher mortality risk than someone sleeping between seven and nine hours.  

Sleep deprivation increases the risk of a variety of diseases. These include hypertension, heart disease, diabetes, obesity, accelerated bone loss, breast, prostate and colon cancers, and infertility. Lack of sleep is also associated with many psychiatric disorders, such as depression, anxiety, mood disorder, bipolar disorder and major depressive disorder. In addition, loss of sleep has been linked to an increased risk of Alzheimer’s disease. A recent study concluded that poor sleep was correlated with changes in gut bacteria, which are associated with gastrointestinal disorders, as well as an increased risk of Parkinson’s disease, depression, anxiety and decreased cognitive function.

Sleep deprivation has negative consequences for military readiness. One study found that service members who regularly slept less than six hours per night were three times more likely to become sick with an upper respiratory infection, compared to soldiers who slept seven or more hours per night. Another study found that a single night of sleep deprivation resulted in significant reductions in marksmanship vigilance and accuracy compared to a well-rested group.  Another study found that military pilot trainee’s performance in a flight simulator was negatively affected by inadequate sleep.

Why do we need sleep? Recent research suggests that nerve cells in the brain (neurons) require sleep in order to repair DNA damage accumulated while our brains are awake. Neuron chromosome activity is much higher at night than in daytime, whereas the brain is less active at night. The low brain activity during sleep makes it easier for neurons to repair DNA damage, providing a mechanism for why sleep is important. Not all sleep is equal to this task, however. Light sleep is not as beneficial as deep sleep for the brain to engage in DNA maintenance.

How does sleep deprivation cause so many health problems? The answer lies in the circadian rhythm system, or our biological clock. The circadian system is a network of individual tissue clocks (heart, muscle, digestive system, etc.) These tissue clocks are coordinated in a part of the brain known as the hypothalamus. This coordination by the hypothalamus is directly synchronized by light to the 24-hour sleep-wake cycle. The circadian clock in the hypothalamus synchronizes a variety of biological functions, such as hormone secretion, skin temperature and heart rate.

Irregular sleep periods, and altered light-dark cycles from shift work and long distance travel causes our circadian clock to go out of rhythm, which desynchronizes many physiologic functions.


Breast and colon cancers. Irregular light cycles switch off genes that suppress tumor growth, and switch on genes which induces the formation of tumors.

Psychiatric disorders. Circadian clock disruption interrupts the normal secretion patterns of melatonin, serotonin and norepinephrine in the brain, which increases the risk of developing depressive/mood/bipolar disorders.

There are several ways you can improve your sleep health. Stop watching television or using cellphones, computers or tablets at least one hour before bedtime. The blue light emitted by these devices tells our brains we should be awake! Alternatives include installing software/apps (f.lux) is one example) which block blue light. If you wear glasses or contact lenses, there are lenses available which also block blue light.

Set your bedroom temperature between 65-69 degrees. Warmer temperatures make it harder to fall asleep. Follow a consistent sleep schedule, which includes waking up at the same time every morning, and don’t try to “catch up” by sleeping later during the weekend. Avoid caffeine within four to six hours of bedtime, and alcohol at least three hours before going to bed. Make sure the bedroom is as dark as possible. If you have electronics in the bedroom, cover those up as well. In addition, refraining from napping is recommended.

For more information on improving sleep, contact Health Promotion Flight at 846-1186. You can also check us out on Facebook (KAFBHealthpromotion) and Twitter (@KirtlandHP.)