How Much Sleep Do You Need?
There is individual variability in how much sleep we need. Most adults need about 7 to 8 hours of good-quality sleep per night (good quality means the major sleep episode does not have frequent arousals and is long enough for the individual).13 Sleep researchers report that the amount of sleep each person needs may be an inherited trait and that it is important to get that amount each day. About 32 percent of U.S. healthcare workers report sleeping 6 hours or less a day,14 which is considered too short by sleep experts.11 Researchers are conducting genetic studies and have identified gene mutations in some people who naturally sleep 6 or less hours a day and appear healthy and function well.15 These people show less deterioration in performance when sleep deprived. The percentage of the population with these gene mutations is estimated to be small. Most people who say they do not need much sleep are pushing themselves to sleep less and as a consequence struggle to stay awake and function during the daytime. Over time they are at risk for obesity and several types of chronic illnesses.16
One way to estimate your sleep-length need is to observe the length of time you sleep toward the end of a relaxing 2-week vacation, when you are not under time pressures and are sleeping freely (awakening spontaneously, without an alarm, and going to bed when you are tired).17 Keep caffeine intake to no more than 2 cups of regular coffee a day (about 200 mg). During the second week, record your bedtimes, wake-up times and length of sleep. The average of the sleep times across 5 to 7 days is an estimate of your sleep-length need.
Some indications of getting enough sleep are feeling refreshed after awakening and not being overly sleepy during the daytime. People who need several cups of regular coffee a day to feel alert may not be getting enough good-quality sleep. The Epworth Sleepiness Scale on the next page is a self-administered test you can use to estimate how your usual level of wake-time sleepiness compares with sleepiness that is likely a concern.18
Awakenings or near-awakenings