Chapter 4: Lesson 4.1 Understanding Sleep 23-24

The Importance of Sleep

How did you feel when you woke up this morning? Did you spring out of bed to face the new day, feeling completely refreshed and rested? Did you hit the snooze button a few times before crawling out of bed, dragging yourself to school, and nearly nodding off in class? How much sleep you get can affect your overall health and wellness (Figure 4.1).

Why Is Sleep Important?

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The Importance of Sleep

If you felt completely refreshed, you likely got an amount of sleep. This means that you got enough sleep to function properly throughout the day. If you find yourself falling asleep in class, however, you likely got an amount of sleep. This means you did not get enough sleep to function. is another term for inadequate. A person who is gets inadequate amounts of sleep.

Getting enough sleep is just as important to as eating well or being physically active. If you do not get enough sleep during the week, you cannot make up for it by sleeping in on the weekend. Getting on a regular basis can lead to health , , and in both school and athletics. For example, people who do not get enough sleep are more likely to get and other types of . People who drive while drowsy are just as likely to have an accident as those who drive while drunk. Students who do not get enough sleep often have trouble paying attention in class.

Sleep Needs and Age

The amount of sleep that a person needs depends on the individual's age (Figure 4.2). , , and need considerably more sleep than adults need. Young people need because their bodies and brains are still developing. the and helps young people .

Some people may need more or less sleep than others. For example, some people are , meaning they can well on less sleep. These people often feel fully awake after sleeping for only . Other people may need more than 9 hours of sleep to feel fully rested.

Think about how much sleep you usually get each night. Do you get enough sleep according to the amounts identified in Figure 4.2? Not meeting these sleep requirements causes people to experience a . This means that they frequently get less sleep than they should. 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 and are very active during sleep, and this activity is 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 and the release of hormones such as melatonin.

are naturally occurring physical, behavioral, and mental changes in the body that typically follow the 24-hour cycle of the sun (Figure 4.3). 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 following:

The is a person's pattern of sleeping in a . The biological clock regulates the sleep-wake cycle in two ways. First, it monitors the amount of . If it senses light, the sends signals in the body that result in activity. If there is less light, the biological clock can send signals to make the . The biological clock also causes a gland located in the brain to release the hormone melatonin when it gets dark. increases feelings of relaxation and sleepiness and signals that it is time to go to sleep.

When the is disrupted, the body’s biological clock takes a while to readjust. This explains , which is a fatigue that people feel after when they travel. When people travel by plane from California to New York, their bodies feel like they “lost” three hours. When their alarms ring the next morning at 7 a.m. in New York, they are tired because it is only 4 a.m. in California according to their biological clocks. Working , adjusting the clock for daylight savings, or simply being exposed to blue light ( ) at night can trick your body into an unnatural circadian rhythm (Figure 4.4).

Stages of Sleep

Each night, you usually pass through four distinct stages of sleep (Figure 4.5). These four stages include non-REM and REM sleep. A complete sleep cycle lasts about 90 to 110 minutes. Over the course of a night, you go through this sleep cycle about four to five times, depending on how long you sleep. The amount of time you spend in each stage of sleep, however, changes as the night progresses.

When a person first falls asleep, they are in non-REM (non-rapid eye movement) sleep. Non-REM sleep is broken out into the first three stages of sleep as follows:

occurs when a person gets drowsy and makes the transition from being awake to falling asleep. is a period of light sleep. In this stage, eye movement stops, heart rate slows, and the body begins to relax. is referred to as deep sleep. This stage is needed for a person to feel rested for the next day.

After the final stage of , a person enters the REM ( ) sleep stage. The first period of REM sleep usually occurs about after you fall asleep. REM sleep is an active stage of sleep during which a person’s breathing changes and becomes irregular, shallow, and more rapid. Heart rate and blood pressure also rise. A person’s about rapidly from side to side under the eyelids, and muscles are temporarily paralyzed.

The cycles of the night contain relatively short REM periods and long periods of deep sleep ( ). The periods of REM sleep get longer with each sleep cycle, while the deep sleep periods get shorter.

There are available that track users’ sleep cycle patterns (Figure 4.6). These apps can identify if the user is getting enough good quality sleep. They also offer techniques and tools for falling and staying asleep. They can even wake the user at the ideal time, while entering the first stage of sleep. It is important to note, however, that many sleep experts do not believe that a sleep app can provide reliable, accurate data regarding a person’s quality of sleep.

Dreaming

Even though you may not remember your , you do dream every night. On most nights, people spend more than two hours dreaming. Many of these dreams will last between . What a person dreams about, however, from night to night. Sometimes dreams may closely relate to what is going on in someone’s . At other times, dreams may appear .

Although most dreams occur during , they can also occur during other sleep stages (Figure 4.7). that occur during REM sleep—when the brain is particularly active—are very vivid. People who wake up at the end of a REM sleep period are more likely to remember their dreams.

How dreams influence a (mental) and physical well-being is unclear because it is difficult to study dreams. This difficulty is because people often forget most of their dreams. Some sleep researchers believe that dreams play a valuable role in daily life. Dreams may provide important information about a person’s deepest feelings, thoughts, and motives. Researchers believe dreams help people do the following:

• remember

• conflicts

• regulate their

Exit Ticket:💡 Something interesting I learned today was .