Copyright Goodheart-Willcox Co., Inc. Chapter 3 Getting the Sleep You Need 69 Figure 3.3 shows general sleep requirements for different age groups. Keep in mind, however, that each person may need more or less sleep. For example, some people are short sleepers, meaning they can function well on less sleep. These people often feel fully awake after sleeping for only 4 to 6 hours. Other people may need more than 9 hours of sleep to feel fully rested. Many people in each age group experience a sleep deficit. This means that they frequently get less sleep than they should. Think about how much sleep you usually get each night. Do you get enough sleep according to the amounts identified in Figure 3.3? Not meeting these sleep requirements causes people to experience a sleep deficit. People might experience a sleep deficit for a variety of reasons. They may go to sleep too late based on when they have to wake up in the morning. Over time, a sleep deficit can result in health concerns. The Science of Sleep The body and brain are very active during sleep, and this activity is essential to staying healthy. This healing activity cannot occur unless you sleep. Systems in your body help you get this necessary rest. Certain mechanisms, or processes, in the body control when you feel tired and when you feel awake. These mechanisms include circadian rhythms and the release of hormones such as melatonin. Circadian rhythms are naturally occurring physical, behavioral, and mental changes in the body that typically follow the 24-hour cycle of the sun (Figure 3.4 on the next page). For example, the body’s temperature drops during the night and rises during the day. Most circadian rhythms are controlled by the body’s master biological “clock.” This “clock” controls circadian rhythms such as the sleep-wake cycle, body temperature, hormone levels, and brain wave activity. Sleep Needs Throughout the Life Span Newborns 14–17 hours Infants 12–16 hours Toddlers 11–14 hours Preschoolers 10–13 hours School-age children 9–12 hours Teenagers 8–10 hours Adults 7–9 hours HOW MUCH SLEEP DO YOU NEED? Clockwise from top left: Ramona Heim/Shutterstock.com Durganand/Shutterstock.com g-stockstudio/Shutterstock.com JPC-PROD/Shutterstock.com Ruslan Guzov/Shutterstock.com Ariwasabi/Shutterstock.com pixelheadstudio digitalskillet/Shutterstock.com Figure 3.3 Sleep needs are not the same for every person across the life span. As you grow, you require fewer hours of sleep each night.