Biological Rhythms, Sleep and Dreaming

Biological rhythms

Natural cycles that regulate physiological processes.

Circadian rhythms

Natural rhythms with a ~24-hour cycle.

Free-running

Circadian rhythm maintained without external cues.

Phase shift

Change in activity due to synchronizing stimulus.

Entrainment

Process of synchronizing biological rhythms.

Zeitgeber

External cue that synchronizes biological rhythms.

Suprachiasmatic nucleus (SCN)

Brain region that regulates circadian rhythms.

Tau mutation in sleep

Genetic alteration causing shorter circadian rhythms.

Melanopsin

Photopigment in ganglion cells for light detection.

Ultradian rhythms

Rhythms occurring more than once per day.

Infradian rhythms

Rhythms occurring less than once per day.

Circannual rhythms

Yearly rhythms influenced by seasonal changes.

Sleep/wake cycle

Most prominent circadian rhythm in humans.

EEG

Electroencephalogram measuring brain electrical activity.

REM sleep

Stage of sleep with rapid eye movement.

NREM sleep

Non-rapid eye movement sleep with multiple stages.

Hypnic jerks

Sudden muscle contractions during Stage 1 sleep.

Sleep spindles

Bursts of brain activity during Stage 2 sleep.

Delta waves

Slow brain waves during deep sleep (SWS).

Night terrors

Sudden arousal from deep sleep with fear.

Dreams

Mental experiences during REM and non-REM sleep.

Infant sleep patterns

Infants sleep more and have shorter cycles.

Elderly sleep changes

Older adults need less sleep and awaken more.

Cognitive decline

Reduced cognitive function often linked to sleep loss.

Basic rest-activity cycle

Ultradian rhythm lasting approximately 90 minutes.

Sustained Sleep Deprivation

Leads to increased metabolic rate and weight loss.

Fatal Familial Insomnia

Genetic defect causing mid-age sleep cessation.

Sleep Deprivation Effects

Causes irritability, concentration difficulty, and disorientation.

Memory Consolidation

Sleep promotes the consolidation of memories.

Energy Conservation

Reduced metabolic activity during sleep for survival.

Niche Adaptation

Sleep adapts organisms to ecological niches.

Body Restoration

Sleep rebuilds body materials and functions.

Forebrain System

Displays slow-wave sleep independently.

Brainstem System

Activates forebrain to induce wakefulness.

Pontine System

Triggers REM sleep through specific brain cells.

Hypothalamic System

Regulates other brain systems for sleep/wake cycles.

Narcolepsy

Characterized by sudden, intense sleep bouts.

Cataplexy

Sudden muscle tone loss without consciousness.

Sleep Enuresis

Bed-wetting occurring during slow-wave sleep.

Somnambulism

Sleepwalking occurring during slow-wave sleep.

REM Behavior Disorder

Acting out dreams, often linked to aging.

Insomnia

Difficulty in falling or maintaining sleep.

Sleep Apnea

Breathing interruptions during sleep, causing health issues.

Sudden Infant Death Syndrome (SIDS)

Possible serotonin system abnormalities affecting respiration.

Benzodiazepines

Recent drugs for insomnia, may cause daytime drowsiness.

Sleep Recovery

Lost sleep cannot be fully recovered.

Prolonged Sleep Deprivation

Hallucinations may occur after over 8 days.

Neurotransmitter Systems

Affected by general anesthetics during sleep.

Basal Forebrain Neurons

Active at sleep onset, promoting sleepiness.

Reticular Formation

Collection of cells promoting wakefulness.

Hypocretin Neurons

Regulate sleep/wakefulness; loss linked to narcolepsy.

NREM Stage 1

8-12Hz (alpha rhythm. Vertex spikes = sharp spikes in EEG.
Hypnic jerks occur in this stage

NREM Stage 2

12-14 Hz. K complexes = sharp negative EEG potentials

NREM Stage 3

~1 Hz Large amplitude, very slow Delta waves

Paradoxical sleep

REM sleep

sleep stage cycle

Lsat about 90 to 110 minutes

NREM dreams

More about thoughts/thinking

REM dreams

vivid, highly visual, often build around stories where the dreamer is present