Sleep and Dreams UNIT 5- RG 5A

Rhythm of Sleep Circadian Rhythms occur on a 24-hour cycle and include sleep and wakefulness Controlled by the hypothalamus, specifically the suprachiasmatic nucleus (SCN) receives input from the eyes & is especially sensitive to the light dark cycles of day and night light signals the SCN to tell the pineal gland to stop release of melatonin…in darkness SCN no longer sends messages, increasing melatonin levels and sleepiness Illustration © Cynthia Turner 2003 Under normal circumstances, the pattern undergoes daily readjustment by our exposure to light and by our habitual routines

The Basic Sleep Cycle The first 90-minutes of sleep We experience 4-6 sleep cycles on an average night.

Sleep Stages 1-4 --“Quiet Sleep” Light sleep Stage 1 – just drifting to sleep, may experience fantastic images and/or auditory hallucinations Stage 2 – more relaxed, clearly asleep – sleep spindles (short bursts of brain activity) occur Deep sleep (brain activity significantly slowed) Stage 3 – transitional stage to deeper sleep Stage 4 – deepest sleep of all, hard to awaken…only occurs during the first few cycles of the night

REM Sleep – Paradoxical Sleep After reaching the deepest sleep stage (4) the sleep cycle starts moving backward towards stage 1. Although still asleep, the brain engages in low amplitude, fast and regular beta waves, much like awake-aroused state. A person in this sleep phase exhibit Rapid Eye Movements (REM) and reports vivid dreams. Brain very active, yet major muscles in body relaxed/paralyzed.

How much sleep do we need? We spend one third of our life sleeping. Genetics influence exactly how much sleep we need…however most humans sleep 9-10 hours if left unhindered. Adults need a bit less sleep than teenagers & children do. OBJECTIVE 18-5| Explain why sleep patterns and duration vary from person to person.

How much sleep do we need? Our brain keeps track of the amount of sleep we get and does not let us “make up” for lost sleep. Once it’s gone, it’s gone. You do, however, tend to get more stage 4 and REM. OBJECTIVE 18-5| Explain why sleep patterns and duration vary from person to person.

Sleep Deprivation Sleep deprivation studies have shown us that sleep is a necessary biological function. If we don’t get enough sleep, we can experience… difficulty focusing diminished productivity greater tendency to make mistakes irritability and fatigue diminished immune system hallucinations (usually after 72 hours) OBJECTIVE 18-6| Discuss several risks associated with sleep deprivation.

Sleep Deprivation The National Sleep Foundation found that over ½ of all American’s are getting less sleep than they need!

Sleep Theories Sleep Protects: Sleeping in the darkness when predators loom kept our ancestors out of harms way. Sleep Recuperates: Sleep helps restore and repair brain (and body) tissue. Sleep Helps Remembering: Sleep restores and rebuilds our fading memories. Sleep and Growth: During sleep pituitary gland releases growth hormone. Older people release less of this hormone and sleep less. OBJECTIVE 18-7| Identify four theories of why we sleep.

Sleep Disorders Insomnia: difficulty falling asleep or staying asleep Narcolepsy: overpowering urge to fall asleep that may occur while talking or standing up Experience sleep attacks that usually last 5 minutes or less…this can mean lapsing directly into REM sleep for some people OBJECTIVE 18-8| Identify major sleep disorders.

Sleep Disorders Night terrors: Sudden arousal from sleep and intense fear accompanied by physiological reactions (occurs usually during 1st cycle) Seems to be related to some fear the child has…but is not the same as a nightmare (bad dream)…just see images If not awakened, child often not remember in the morning Sleep apnea: Failure to breathe when asleep Wake up (100s) of times a night so begin breathing again Treatments include weight loss and CPAP machine

Sleep Disorders Sleepwalking: blank stare, move about in a slow/automatic manner and may try to eat, dress, or go to the bathroom in the wrong place occurs in stage 4 sleep technical name…somnambulism REM Behavior Disorder (RBD): muscles not paralyzed in REM, allowing person to act out their dreams (usually the vivid, violent, intense dreams) Seen more often in middle-age/elderly men, sometimes linked with Parkinson’s disease

Dreams Usually story-like unfolding mental imagery – most commonly dreams have some degree of likeness to daily activities, yet tend to be more bizarre and unrealistic

What do we Dream? What are some common themes in YOUR dreams? Have you ever had a recurring dream?

Dreams Questionnaire… 1000 Psychology Today readers responded… 95% said they remembered their dreams 39% said they could control their dreams 68% said they had a recurring dream 28% said they had died in a dream 45% said they had dreamed about celebrities

Why do we dream? Wish Fulfillment: Sigmund Freud suggested the dreams provide a safety valve to discharge unconscious wants & desires. The manifest content (remembered story-line) is a censored version of the dream’s latent content (underlying meaning of dream) Information Processing: Dreams may help sift, sort, and fix day’s experiences in our memories. OBJECTIVE 18-10| Compare the major perspectives on why we dream.

Why do we dream? Physiological Function: Dreams provide sleeping brain with periodic stimulation to develop and preserve neural pathways. Neural networks of newborn are fast developing therefore need more sleep.

Why do we dream? Activation-Synthesis Theory: Suggests that the brain engages in a lot of neural activity that is random. Dreams make sense of this activity. dreams are the brain’s interpretations of its own activity SO… they mean NOTHING!!!

Why do we dream? Cognitive Development: Some researchers argue that we dream as a part of brain maturation and cognitive development. All dream researchers believe we need REM sleep. When deprived of REM sleep, and then allowed to sleep, we show increased REM sleep called REM Rebound.

Dream Theories Summary