Sleep and Dreams Summary

Biological Rhythms and Sleep

  • Two biological rhythms: 24-hour biological clock and 90-minute sleep cycle.

  • Circadian rhythm: Internal biological clock, altered by age and experience, influencing "night owls" versus "morning types."

  • REM (rapid eye movement, R sleep): Rapid, saw-toothed brain waves; increased heart rate, rapid and irregular breathing; darting eyes; genital arousal; motor cortex messages blocked by brainstem; paradoxical sleep; protective paralysis.

  • Beta waves (alert, waking state) and alpha waves (awake, relaxed state) differ from delta waves (deep N3 sleep).

  • REM sleep waves resemble N1 sleep waves, but the body is more internally aroused during REM than NREM sleep.

  • Sleep patterns are affected by genetic, cultural, social, and economic influences.

  • Light impacts the biological clock via light-sensitive retinal proteins and the suprachiasmatic nucleus (SCN), which decreases melatonin production.

  • Irregular sleep schedules and night-shift work can cause desynchronization.

  • Sleep functions include protection, recuperation, memory restoration, creative thinking, and supporting growth.

Sleep Deprivation and Sleep Disorders

  • Sleep loss: Accumulation of sleep debts, requiring weeks for recovery; unrestricted sleep averages 7.5-9 hours after debt is paid.

  • Effects of sleep deprivation:

    • Mood changes (testiness, anger, conflicts).

    • Increased risk of depressive disorders and suicidal thoughts.

    • Potential weight gain due to hormonal and metabolic disruption (increased ghrelin, decreased leptin, increased cortisol, decreased metabolic rate).

    • Disrupted gene expression, increasing risks for heart disease and other negative health outcomes.

    • Enhanced limbic responses to food and decreased ability to resist temptation.

    • Suppressed immune cells.

    • Slower reactions and increased errors on visual attention tasks.

  • Major sleep disorders:

    • Insomnia

    • Narcolepsy

    • Sleep apnea

    • Sleepwalking and sleeptalking

    • Night terrors

Dreams

  • 8/10 dreams contain negative events/emotions like failing, being attacked/pursued/rejected, or experiencing misfortune.

  • Sexual content appears in 1/10 dreams for men and 1/30 dreams for women.

  • Common dream content is influenced by trauma, music, sense use, and media experiences.

  • Why we dream (theories):

    • Freud’s wish fulfillment (manifest and latent content).

    • Information processing (filing away memories).

    • Physiological function (developing/preserving neural pathways).

    • Activation-synthesis (making sense of neural static).

    • Cognitive theory (reflecting cognitive development).