SLEEP

Question 1

BIOLOGICAL RYTHMS

Answer 1

− Sleep is affected by biological rhythms or periodic physiological changes.
− Biological rhythms are regular, periodic changes in a body’s functioning
− There are three types of biological rhythms: CIRCADIAN, INFRADIAN, ULTRARADIAN

Question 2

CIRCADIAN RYTHMS

Answer 2

− Biological cycles that occur about every twenty-four hours.
− Sleep follows a circadian rhythm.
− Hormone secretion, blood pressure, body temperature, and urine production also have circadian rhythms.

Question 3

INFRADIAN RYTHMS

Answer 3

− Biological cycles that take longer than twenty-four hours. For example, women’s menstrual cycles occur about every twenty-eight days

Question 4

ULTRADIAN RYTHMS

Answer 4

− Biological cycles that occur more than once a day.
− Sleep follows an ultradian rhythm of about ninety minutes as well as a circadian rhythm.
− Alertness and hormone levels also follow ultradian rhythms.

Question 5

BIOLOGICAL CLOCKS

Answer 5

− Endogenous rhythms exist because the body has biological clocks that keep time.
− Biological clocks can be adjusted by environmental cues, such as changes in temperature.

Question 6

BC IN HUMANS

Answer 6

− the suprachiasmatic nucleus (SCN) is the main biological clock that regulates circadian rhythms of sleep.
− The SCN lies in the brain’s hypothalamus.
− When light stimulates receptors in the retina of the eye, the receptors send signals to the SCN.
− The SCN then sends signals to the nearby pineal gland, which secretes melatonin, a hormone that regulates the sleep cycle.

Question 7

JET LAG

Answer 7

− Jet lag is the fatigue and disorientation air travelers feel after a long flight. Although traveling itself drains energy, the time change also contributes to fatigue.
− People experience jet lag when the events in their environment are out of sync with their biological clocks.

Question 8

THE FUNCTION OF SLEEP

Answer 8

− People conserve energy by sleeping periodically.
− Sleep has a protective function, as it keeps people tucked away at night, safe from predators.
− Sleep restores body tissues that are depleted during daily activities.

Question 9

EEGS

Answer 9

• Electroencephalographs

- Record BRAIN WAVES

Question 10

EMGS

Answer 10

• Electromyographs

- Record MUSCLE ACTIVITY

Question 11

EOGS

Answer 11

• Electrooculography

- RECORD EYE MOVEMENT

Question 12

EKGS

Answer 12

• Electrocardiographs

- Record HEART ACTIVITY

Question 13

SLEEP STAGES

Answer 13

• 1, 2, 3, 4, REM (5 stages in cycle)

- Each lasts 90-100 minutes

Question 14

SLEEP STAGE 1

Answer 14

− When people are relaxed and ready to fall asleep, their EEG will show mostly alpha waves.
− When people fall asleep, they enter into stage 1 sleep, which lasts just a few minutes.
− In stage 1, the EEG shows mostly theta waves.
− Heart rate, breathing rate, and body temperature drop, and muscles relax.
− Fantasies or bizarre images may float around in the mind. After a few minutes of stage 1 sleep, people move into stage 2 sleep.

Question 15

SLEEP STAGE 2

Answer 15

− Stage 2 lasts about twenty minutes and is characterized by short bursts of brain waves called sleep spindles

Question 16

SLEEP STAGE 3-4

Answer 16

− In stages 3 and 4, which together last about thirty minutes, the EEG displays mostly delta waves.
− People in stage 3 and 4 sleep show slow breathing and pulse rates, have limp muscles, and are difficult to rouse.

Question 17

SLEEP WALKING

Answer 17

− Most people in stage 4 sleep are still, quiet, and difficult to rouse.
− Sleepwalkers, however, sometimes become physically active during stage 4.
− They may get up and walk around their room or even carry on a conversation, take a bath, cook, or go outside and get in their car.
− Because they are in a deep sleep, most sleepwalkers remember nothing of their actions when they wake up.

Question 18

REM SLEEP

Answer 18

− At the end of stage 4, people go back through the stages in reverse, from stage 4 to 3 to 2 to 1. When they reach stage 1, instead of waking up, people go into REM, or rapid eye movement, sleep. A single cycle might look like this: 1 2 3 4 3 2 REM
− REM sleep is a stage of deep sleep in which, paradoxically, brain wave activity resembles that of an alert person. REM sleep is also called paradoxical sleep.
− During REM sleep, pulse rate and breathing become irregular, eyes move rapidly under closed lids, and muscles remain very relaxed.
− EEGs show mostly beta waves during REM sleep.
− Although dreaming happens in other sleep stages as well, dreams are most vivid and frequent during REM sleep.
− People typically go through about four sleep cycles during one night of sleep.
− The REM stage of sleep gets longer and longer as the night passes, while stage 3 and 4 sleep gets shorter and shorter.
− During the night’s first sleep cycle, the REM stage lasts about ten minutes. During the night’s last sleep cycle, people may spend about forty to sixty minutes in REM sleep.
− Non-REM sleep becomes shallower as the night goes on, and eventually the sleeper awakens.

Question 19

SLEEP DEPRIVATION

Answer 19

− Different people need different amounts of sleep.
− Some people can function with fewer than six hours of sleep a night, while others can’t manage without at least nine hours.
− Research shows that getting insufficient sleep can have negative effects on health, productivity, and performance.
− Researchers have also studied the effects of insufficient REM sleep.
− Experiment subjects who are intentionally deprived of REM sleep tend to enter the REM stage of sleep more and more frequently during the night
− After an REM-deprivation experiment has ended, subjects usually experience a REM rebound effect, spending more time in the REM stage on subsequent nights to make up for lost REM time.

Question 20

AGING AND SLEEP

Answer 20

− Sleep patterns change as people get older.
− Newborn babies spend about two-thirds of their time in sleep.
− As people age, they tend to sleep less.
− The amount of time spent in REM sleep also changes over time. In very young babies, about half of all sleep is REM sleep.
− As babies get older, the proportion of REM sleep decreases.

Question 21

SLEEP DISORDERS

Answer 21

− Everyone has occasional difficulty sleeping, but some people have insomnia, a chronic problem with falling or staying asleep.
− Another kind of sleep disorder is narcolepsy, which is a tendency to fall asleep periodically during the day.
− Narcolepsy can be dangerous, as people who experience it may fall asleep while driving or operating machinery.
− Sleep apnea is another condition that can have negative effects on health and safety.
− People who have sleep apnea stop breathing many times during a night’s sleep, and each time they stop breathing, they wake up briefly and gasp for air.
− This prevents them from getting enough deep sleep, which leads to irritability and sleepiness during the day.
− Chronic sleep apnea can also result in high blood pressure.