Getting enough sleep is a struggle for at least a quarter of adult Americans, but how much is really enough? Clarissa Leahy/Getty Images

For the first two years of his life, my son slept for just two hours at a time. By default, I only slept that long, too. I managed for more than a year, making up the difference by catching a catnap here and there, or sleeping more on weekends. Then one day as I was driving to work — a route I'd taken hundreds of times before — I couldn't remember which exit to take. For a moment, I wasn't even sure why I was driving down the road at all. I pulled over, gathered my wits about me and returned home to spend the rest of the day sleeping and mapping out a new sleep strategy that would ensure my survival.

Clearly, I was sleep deprived. The incident left me wondering: How much sleep do we actually need? Turns out, it varies, and most of the variance depends on age. In general, the younger the person, the more sleep he or she needs.



According to the latest info from the National Sleep Foundation, newborns need 14 to 17 hours of sleep in a 24-hour cycle, while infants up to 11 months old need 12 to 15 hours of shuteye. From there, the sleep requirements begin to wane [source: NSF]:

1 to 2 years of age: 11 to 14 hours

3 to 5 years: 10 to 13 hours

6 to 13 years: 9 to 11 hours

14 to 17 years: 8 to 10 hours

18 to 25 years: 7 to 9 hours

26 to 64 years: 7 to 9 hours

65 and older: 7 to 8 hours

There are a number of other factors that can affect the amount of sleep you need. During the first trimester of pregnancy, for example, most women find themselves sleeping more. And, even though adults 65 and older need fewer hours of sleep than other age groups, they may sleep fitfully and stay in bed longer trying to make up for it. The same is true for people of any age who have interrupted sleep; they may have trouble waking once they finally fall asleep or feel like it's difficult to get out of bed altogether. Neurological conditions, such as Parkinson's disease, can cause excessive sleepiness. So can medical conditions like iron deficiencies or low thyroid function [sources: Morgenthaler, NSF].

Getting enough sleep is a struggle for at least a quarter of adult Americans who report they can't establish regular sleep patterns [source: Pearson]. So the next time you're pouring a bowl of cereal by the light of an open refrigerator door at 2 a.m., just remember that you're not alone. And consider consulting your doctor if you're sleeping for much less or much more than seven hours per night. Not only might it have a more serious cause, but sleep problems may put you at risk of health problems or a higher mortality rate [source: Morgenthaler].