What is the nature of sleep? Most people think of sleep as a state of unconsciousness, punctuated by brief periods of dreaming. Sleep is actually a state of altered consciousness, characterized by certain patterns of brain activity and inactivity.

Facts about Sleep Most adults need seven or eight hours' sleep a night A giraffe sleeps for an average of 1.9 hours a day A cat sleeps for an average of 12 hours a day Famous figures like, Margaret Thatcher, Napoleon and Florence Nightingale only needed four hours An adult sleeping for eight hours will burn approximately 50 calories Almost two thirds of the population claim they do not get enough sleep

Why do we sleep? While the exact function of sleep is unknown, but according to the evolutionary theory, sleep evolved to conserve energy and protect us from predators. According to the repair/restoration theory, sleep is thought to be necessary for restorative/healing value, both physically and psychologically.

Loss of Sleep… suppressed immune system impaired creativity and concentration slowed performance and misperceptions on monotonous tasks

Benefits of Sleep restoration of energy repairing of brain and body tissue release of growth hormones

Stages of Sleep Each night, we go through four to five cycles of distinct sleep stages. Each stage has its own rhythm and corresponding changes in brain activity and behavior. The average person progresses through the stages of sleep 3 to 6 times per night. portal.com/academy/lesson/sleep- cycle.html#lesson

Stage 0 This period of falling asleep is also called the hypnagogic state. (hip-na-gog-ic) relaxed with eyes closed brain briefly emits alpha waves = associated with absence of concentrated thought and relaxation

Stage I sensory images and slow rolling eye movements theta waves on an EEG-- lower in amplitude and frequency than alpha waves pulse slows more, muscles relax, breathing uneven If awakened during this stage, you would report that you were “just drifting.” Lasts from 30 seconds to about 10 mins.

Stage II Brain waves shift from low-frequency waves to high frequency waves Eyes roll slowly from side to side About 50% of our sleep time is in stage II

Stage III About 30 minutes into sleep= drift down into a deeper level of sleep larger-amplitude delta waves begin to sweep your brain every second or so

Stage IV Deepest sleep of all Often difficult to wake Large, regular Delta Waves occurring more than 50% of the time If awakened by a loud noise = may feel disorientated Talking out loud, sleepwalking, and bed- wetting—all of which may occur at this stage—leave no trace on the memory

Rapid Eye Movement =REM sleep muscles are more relaxed, eyes begin to move rapidly pulse rate becomes irregular levels of adrenal and sexual hormones in blood rise face or fingers twitch large muscles in your arms and legs are paralyzed brain shows waves that closely resemble those of a person fully awake = REM sleep is called active sleep

Stages of Sleep--REM Stages I-IV are called NREM (non- REM) or quiet sleep. It is during REM sleep that almost all dreaming normally takes place. REM sleep lasts about minutes after which you retrace the steps to Stage IV.

Sleep Disorders: When Sleep Becomes a Problem Are you one of those lucky people who takes sleep for granted? If so you may be surprised to discover the following facts: An estimated 2/3 of adults suffer from sleep problems and about 25 percent of children under age 5 have a sleep disturbance One in five adults is so sleepy during the day that sleepiness interferes with their daily activities. Each year [Americans] spend more than $98 million on over-the-counter sleep aids and another $50 million on coffee to keep them awake during the day.

Sleep Disorders: Dyssomnia & Parasomnia Psychologists divide sleep disorders into two major diagnostic categories: 1) Dyssomnias: problems in the amount, timing, and quality of sleep 2) Parasomnia: abnormal disturbances occurring during sleep

Sleep Disorders: Dyssomnia Insomnia : “lack of sleep” persistent difficulty falling asleep or staying asleep, or wake up too early 10% of the population serious insomnia = other medical or psychological disorders also (alcohol and other drug abuse, anxiety disorders, and depression) most popular treatment = drugs—either over the counter pills or prescription tranquillizers and barbiturates (which decrease Stage 4 and REM sleep therefore affect the quality of sleep)

Sleep Disorders: Dyssomnia Sleep Apnea: “no breathing” repeated interruption of breathing during sleep air passages to the lungs are physically blocked or the brain stops activating the diaphragm may kill neurons in the brain critical for learning and memory can also lead to high blood pressure, stroke, heart attack

Sleep Disorders: Dyssomnia Narcolepsy: sudden and irresistible onset of sleep during normal waking hours afflicts one person in 2000 runs in families REM-like sleep suddenly intrudes into the waking state of consciousness sudden attacks of muscle weakness or paralysis Long daily naps and stimulant or antidepressants may help reduce the frequency

Sleep Disorders: Parasomnias Nightmares: Anxiety-arousing dreams generally occurring near the end of the sleep cycle, during REM sleep Night Terrors: Abrupt awakenings from NREM (non- rapid-eye-movement) sleep accompanied by intense psychological arousal and feeling panic Sleep walking: Tends to accompany night terrors also occurs during NREM sleep. Sleep talking occurs in REM and NREM sleep These events are more common in children, but they can also occur in adults, usually during times of stress or major life events.

Help with Sleep Disorders During the Day : Exercise—it works away tension Avoid Stimulants—coffee, tea, soft drinks, chocolate Avoid Late Meals & Heavy Drinking Stop Worrying—focus on problems at a set time earlier in the day Use Pre-sleep Rituals—follow the same routine every night In Bed: Use progressive muscle relaxation-tense and relax muscle groups Yoga-type gentle exercises to help relaxation Imagine yourself in a tranquil setting Use deep breathing Warm bath or shower can induce drowsiness

Psychoactive Drugs Overview: portal.com/academy/lesson/psychoactive- drugs.html#lesson portal.com/academy/lesson/psychoactive- drugs.html#lesson