The amount of sleep you need depends on various factors — especially your age. Consider these general guidelines for different age groups:

In addition to age, other factors can affect how many hours of sleep you need. For example:

• Pregnancy. Changes in a woman's body during early pregnancy can increase the need for sleep.
• Aging. Older adults need about the same amount of sleep as younger adults. As you get older, however, your sleeping patterns might change. Older adults tend to sleep more lightly and for shorter time spans than do younger adults. This might create a need for spending more time in bed to get enough sleep, or a tendency toward daytime napping.
• Previous sleep deprivation. If you're sleep deprived, the amount of sleep you need increases.
• Sleep quality. If your sleep is frequently interrupted or cut short, you're not getting quality sleep. The quality of your sleep is just as important as the quantity.

Although some people claim to feel rested on just a few hours of sleep a night, research shows that people who sleep so little over many nights don't perform as well on complex mental tasks as do people who get closer to seven hours of sleep a night. Studies among adults also show that getting less or much more than seven hours of sleep a night is associated with a higher mortality rate.

If you experience frequent daytime sleepiness, even after increasing the amount of quality sleep you get, consult your doctor. He or she might be able to identify any underlying causes — and help you get a better night's sleep.

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Apr. 20, 2013 See more Expert Answers