In April of this year, the Institute of Medicine issued a report that confirmed definite links between sleep deprivation and increased risks of hypertension, diabetes, obesity, depression, heart attack and stroke.
Some scientists are also investigating connections between insufficient sleep and depressed immune function.
Sleep can work to activate or inhibit hormone production in the hypothalamus, which is the part of the brain that gives the body signals regarding when to adjust temperature, blood pressure, digestive secretions and immune activity. Insufficient sleep also inhibits the pancreas from producing insulin, the hormone required for the digestion of glucose.
A groundbreaking 1999 study showed that after six days on only four hours of sleep, healthy volunteers would fall into a pre-diabetic state. Sleep also gives the heart a chance to slow down, and those who less than six hours a night have as much as a 66 percent greater prevalence of hypertension.
The largest study of sleep duration and mortality followed over one million participants for six years. Those who slept about seven hours had the highest survival rate, and those who slept less than 4.5 hours had the worst. Nine hours of sleep or more each night was also associated with a higher mortality risk, however.In general, a good night's sleep seems to be as important to good health as a nutritious diet and regular exercise. Experts tend to agree that the majority of people require about eight hours of sleep each night.
However, roughly 40 percent of Americans get fewer than seven hours of sleep on weekdays, and 71 percent get fewer than eight hours of sleep. As a result, most Americans accumulate two full weeks of "sleep debt" each year. The two main causes for sleep debt were long work hours and long commutes.