How much sleep does a person need?

There is no hard and fast answer to this question. The amount of sleep a person needs depends on many things, including age. Most adults need at least 7 to 8 hours of sleep per night, although some people may need as many as 10 hours. Children and adolescents need about 9 hours of sleep, while young infants may need around 16 hours per day. Women in the first 3 months of pregnancy often need a few more hours of sleep than normal, and sleep quality is decreased. When people sleep too little over a period of a few days, they build up a "sleep debt," like being overdrawn at a bank. This debt needs to be repaid sooner or later. A person's body is not able to get used to less sleep than they need. Aging does not seem to change the amount of sleep a person needs, although older people tend to sleep more lightly and for shorter periods of time. About half of the people over 65 have frequent sleeping problems, such as insomnia, and deep sleep stages that are shortened or completely stopped. These changes in sleep may be a normal part of aging, or can be caused by medications or treatments for other health problems.