Is there a magic number of hours you should sleep? According to studies on sleep and mortality, insufficient sleep can shorten your life. Sleeping plays an important role in:
- Healing and repairing blood vessels
- Maintaining a healthy balance of hormones that control your appetite
- Controlling blood glucose (sugar)
- Repairing cells and tissues, thus boosting bone/muscle mass
- Defending against foreign or harmful substances
You can experience the following immediate and long-term health effects when you don’t get enough sleep:
- Diminished cognitive function
- Increased levels of cortisol (stress hormone) which cause the following:
- Increased appetite / See video: Undersleeping and Overeating
- Increased body weight
- Increased belly fat / See video: Beer Belly Anatomy 101
- Increased risk for type 2 diabetes
- Increased chronic low-level inflammation which leads to chronic disease (such as, coronary artery disease, dementia, and stroke)
- Increased blood pressure
If Seven is Good, Is Eight Better?
Many people believe that they need at least eight hours of sleep a night for good health. But a study* reveals that sleeping seven (7) hours per night had the best survival rates. In fact, mortality hazard significantly increased when sleeping:
- 8 hours or more (When sleeping more than 8.5 hours, health risk exceeded 15%.)
- 6 hours or less (When sleeping less than 4.5 hours, health risk exceeded 15%.)
Causes of death associated with sleep duration include:
- Heart disease
- ‘Other causes’
- Cancer
- Stroke (Deaths from stroke were highest in men and women who slept 8, 9, and 10 or more hours)
- Breast cancer
- Colon cancer
Bottom line: Those who reported they slept 6.5 to 7.4 hours had a lower mortality rate than those with shorter or longer sleep.
*Six-year study by American Cancer Society; 1.1 million men/women ages 30-50 to >70 years. Published JAMA Psychiatry article: Mortality Associated With Sleep Duration and Insomnia, 2002.
