Sleep Disorders

How Much Sleep Does a Person Need?

The amount of sleep each person needs depends on many factors, including age, health, recent physical exertion, and mental activity.

Infants sleep about 16 hours a day, while teenagers need about 9 hours on average. For most adults, 7 to 8 hours a night appears to be the best amount of sleep, although some people may need as few as 5 hours or as many as 10 hours of sleep each day. There is quite a bit of variation.

Don’t assume you are at one end of the spectrum unless you have paid close attention to your body. If you are drowsy during the day, even during boring periods, you haven’t had enough sleep the previous night. Most people experience a dip in early afternoon – siesta time.

Sleep deprivation – even one or two nights – can vastly affect your need for sleep. Unlike many things in life, sleep time is not something that is routinely changed. You can’t get used to a lower amount of sleep just because it fits your schedule. If you try to, it will affect your judgment and reaction time, even if you are not consciously aware of it.

If you routinely fall asleep within 5 minutes of lying down, you probably have severe sleep deprivation or a sleep disorder. Microsleeps, or very brief episodes of sleep in an otherwise awake person, are another mark of sleep deprivation. In many cases, people are not aware that they are experiencing microsleeps. The widespread practice of "burning the candle at both ends" in western industrialized societies has created so much sleep deprivation that what is really abnormal sleepiness is now almost the norm.

Sometimes you’ll hear that you need less sleep as you get older. But that is incorrect. Seniors often sleep less than young adults and children because they have insomnia. Also, deep sleep stages (stages 3 and 4) in many elderly people declines to a lower percentage of total sleep time, and may even stop completely. People often feel the decline in stages 3 and 4 sleep represents a decline in sleep quality, and they would prefer that it not happen.

Is this newfound insomnia normal? It’s hard to say for any individual person. Some experts consider insomnia a normal part of aging, or it may result from medical problems that are common in elderly people and from the medications and other treatments for those problems. A recent Dutch study found that older people who slept a lot had higher cholesterol levels and lower good high-density cholesterol than those who slept less.

"Eight hours they give to sleep" – Sir Thomas Moore - Utopia, 1551

The master sleeper.

The Organization for Economic Co-operation and Development (OECD) published a survey showing that citizens of France get more sleep, on average, than any other country in the OECD. The average Japanese person sleeps almost an hour a night less than the average French person. The United States was second, right behind France, of the countries considered.