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How Much Sleep Do You Need?

Sleep is a great mystery. A trait shared across animal species, sleep must be of vital importance to survive natural selection pressures to eliminate such a vulnerable state. Sleeping too little and for too long are both associated with cutting one’s life short, with the apparent sweet spot at seven hours a night.

One function of sleep that has been elucidated in recent years is the clearance of toxic waste substances through a recently discovered drainage system in the brain. This could help explain why those who routinely sleep fewer than seven hours a night are at increased risk of developing cognitive disorders, such as dementia. The lowest risk for developing cognitive impairment was found for those getting seven to eight hours of sleep a night, and the same range was found for diabetes. Lack of sleep, or even too much of it, is also associated with increased stroke risk. Higher stroke rates have been found among individuals sleeping six hours or less, or nine hours or more, and those at lowest risk got around seven or eight hours of sleep a night.


How to Improve Sleep Quality

To improve our sleep, pills are a no-go. A significant association has been found between sleeping pills and premature deaths. Fatalities aside, nonpharmacological methods have been found to work as well or even better than drugs—and without side effects. Tart cherries, goji berries, and kiwi, for example, have been shown to help improve sleep.

Four Rules of Sleep Conditioning:

  1. Go to bed only when you’re sleepy.
  2. Only use the bed for sleep (and sex). No reading, eating, or screen time.
  3. If you can’t fall asleep within fifteen to twenty minutes or so, get up, leave the bedroom, and don’t go back until you’re sleepy again. Repeat as necessary.
  4. Get up at the same time every morning no matter how little sleep you have had.

Four Rules of Sleep Hygiene:

  1. Exercise regularly.
  2. Avoid caffeine, nicotine, and alcohol before bedtime.
  3. Make the bedroom dark, cool, comfortable, and quiet.
  4. Establish a relaxing bedtime routine.

The information on this page has been compiled from Dr. Greger’s research. Sources for each video listed can be found by going to the video’s page and clicking on the Sources Cited tab. References may also be found at the back of his books.

Image Credit: Quin Stevenson / Unsplash. This image has been modified.

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