This is not an easy question to answer. The National Sleep Foundation offers ranges for various ages, but with the range for adults being two whole hours, from seven to nine hours, it is certainly not definitive.
Time Magazine quoted Daniel Kripke, co-director of research at the Scripps Clinic Sleep Center in La Jolla, Calif., who compared death rates among more than one million American adults who reported their average nightly amount of sleep. While his results were surprising, they have since been corroborated by similar studies in Europe and East Asia.
“Studies show that people who sleep between 6.5 hr. and 7.5 hr. a night, as they report, live the longest. And people who sleep 8 hr. or more, or less than 6.5 hr., they don’t live quite as long. There is just as much risk associated with sleeping too long as with sleeping too short. The big surprise is that long sleep seems to start at 8 hr. Sleeping 8.5 hr. might really be a little worse than sleeping 5 hr.” Kripke said.
“Morbidity [or sickness] is also “U-shaped” in the sense that both very short sleep and very long sleep are associated with many illnesses—with depression, with obesity—and therefore with heart disease—and so forth. But the [ideal amount of sleep] for different health measures isn’t all in the same place. Most of the low points are at 7 or 8 hr., but there are some at 6 hr. and even at 9 hr. I think diabetes is lowest in 7-hr. sleepers [for example]. But these measures aren’t as clear as the mortality data.”
The best explanation I have heard was from Associate Professor Ramadevi Gourineni in Neurology and Director of the Insomnia Program speaking before the Northwestern Memorial Hospital’s Healthy Transitions Program®. In answer to the question how much sleep do I need, she offered, “The amount that permits us to be wide awake, alert and energetic throughout the day. This amount varies from person to person and may be genetically determined.” She also noted that not only do we need the proper quantity of sleep, but also the proper quality of sleep. Continue reading