Researchers generally agree on the number of hours people need at various stages in life. And because those sleep requirements change as you age, it's important to understand what your goals should be and how to address sleep problems if you're not getting enough sleep (or, for a smaller percentage of people, too much sleep). In addition to knowing how much sleep you should get, it's important to understand that when you sleep affects your physical and mental health, too. You can make wise nighttime choices the more you see how your hours of sleep fit into your circadian rhythm, that 24-hour "biological clock" covering everything from sleep and digestion to blood pressure, hormone secretion and more.
Quantity
In general, you'll need less sleep as you move from infancy through childhood and the teen years and on into adulthood. Sleep expert Kenneth Berge, MD, writes on the Mayo Clinic website, "Infants typically sleep at least 16 hours a day. Most preschoolers need at least 11 hours of sleep a night, and most school-age children need at least 10 hours of sleep a night. By the teenage years, nine hours of sleep a night is usually adequate. For most adults, seven to eight hours a night seems about right."
Teen Sleep Time
In addition to how many hours of sleep we need, it appears that when those hours are actually accumulated matters, too. According to the National Institutes of Health's "Guide to Healthy Sleep," physical changes in adolescence help shift circadian rhythms and result in teens typically getting seven to seven and a half hours of sleep, less than their bodies demand. The report states, "The hormonal influences of puberty tend to shift adolescents' biological clocks. As a result, teenagers are more likely to go to bed later than younger children and adults, and they tend to want to sleep later in the morning. This sleep-wake rhythm is contrary to the early-morning start times of many high schools."
Sleep Quality
People not only get less sleep as they age, but the quality of sleep tends to diminish, too. This can be due to many reasons, including medications that may interfere with sleep; conditions that can cause pain, such as arthritis or bladder problems that may necessitate bathroom trips in the middle of the night; lack of exercise; stress; and poor sleep hygiene (your nighttime routine). As you age, you also spend less time in the deep sleep stage and more in the lighter sleep stages, and as a result are more easily awakened.
The Sleep Bank
The phrase "catch up on some sleep" isn't just wishful thinking on the part of weary individuals. Sleep experts acknowledge that you can make up for sleep-deprived nights with a nap or a good night's rest. It's not advisable to count on making frequent catch-up deposits in the sleep bank, but it is important to listen to your body and sleep when it's telling you to do just that. Your mind and body know when they need more sleep to feel restored and healthy. Unfortunately, you can't really "save up" on sleep by resting for a long period before pulling an all-nighter.
Sleep and Your Heart
Quality sleep should begin before midnight to help preserve heart health, according to a Japanese study presented at the 2009 American College of Cardiology conference. The study found that men who went to bed before midnight had significantly less arterial stiffening, an early sign of atherosclerosis, than men who went to bed after midnight. Though the reasons remain unclear, researchers believe that later bedtime may simply disrupt the body's natural biological rhythms and sleep patterns.
