Sleep

Endogenous - “generated from within”

Endogenous Circannual Rhythm - yearly

Endogenous Circadian Rhythm - daily

Zeitgeber “time-giver” - stimulus that resets the circadian rhythm

light - by far the most dominant zeitgeber for land animals 

Jet Lag - a disruption of circadian rhythms due to crossing time zones

Cortisol - Stress hormone. Prolonged elevations of cortisol damage neurons in the hippocampus, a brain area important for memory.

Morning people “larks”

Evening people “owls”

SUPRACHIASMATIC NUCLEUS - just above “supra” the optic chiasm. The main driver of rhythms for sleep and body temperature. Generates circadian rhythms itself in a genetically controlled manner.

Retinohypothalamic path - a small branch of the optic nerve from the retina to the SCN that alters the SCN’s settings.

Melatonin - a hormone released by the Pineal Gland. In diurnal animals like humans, it increases sleepiness. In nocturnal animals, it increases wakefulness.

Coma - extended period of unconsciousness caused by head trauma, stroke, or disease. 

Vegetative State - Alternates between periods of sleep and moderate arousal, although even during the aroused state, the person shows no awareness of surroundings and no purposeful behavior.

Brain Death - a condition with no sign of brain activity and no response to any stimulus.

STAGE 2 SLEEP - consists of K-complex and Sleep Spindles.

K-Complex - a sharp wave associated with temporary inhibition of neuronal firing.

Sleep Spindle - a burst of 12-14 Hz waves for at least half a second.

Paradoxical Sleep - Deep sleep in some ways and light in others. Term used in species that lack eye movements. 

Reticular Formation - a structure that extends from the medulla into the forebrain. Some neurons have axons descending into the spinal cord.

Pontomesencephalon - one part of the reticular formation that contributes to the cortical arousal.

GABA - inhibits or interrupts behavior and promotes slow-wave sleep.

Locus Coeruleus - a small structure in the pons, is usually inactive, esp during sleep, but emits bursts of impulses in response to meaningful events, esp those that produce emotional arousal. 

Histamine - an excitatory neurotransmitter which enhances arousal and alertness throughout the brain.

Antihistamine - used for allergies, counteract this neurotransmitter and produce drowsiness. 

Orexin / Hypocretin - enhances wakefulness and activity.

Acetylcholine - stimulates the basal forebrain cells that promote wakefulness, although those cells release other transmitters to the cortex.

Somnambulism - aka sleepwalking

Lucid Dreaming - someone is dreaming but aware of being asleep and dreaming.

PONS-GENICULATE-OCCIPITAL (PGO) - A distinctive pattern of high-amplitude electrical potentials that associate with REM sleep.

Insomnia - inadequate sleep

Sleep Apnea - impaired ability to breathe while sleeping.

Narcolepsy - frequent periods of sleepiness during the day. Symptoms:

  1. Attacks of sleepiness during the day

  2. Occasional Cataplexy - attack of muscle weakness when the person remains awake.

  3. Sleep Paralysis - inability to move while falling asleep or waking up.

  4. Hypnagogic Hallucinations - dreamlike experiences that the person has trouble distinguishing from reality.

Periodic Limb Movement Disorder - repeated involuntary movement of the legs and arms during sleep. 

REM Behavior Disorder - people move around vigorously during REM periods, apparently acting out their dreams.

Night Terrors - experiences of intense anxiety from which a person awakens screaming in terror. 

FUNCTIONS OF SLEEP 

  • Energy Conservation

  • Improved Memory 

PHENOMENON OF LONG-TERM POTENTIATION - the ability of new experiences to strengthen synaptic connections. 

ACTIVATION-SYNTHESIS HYPOTHESIS - A dream represents the brain’s effort to make sense of sparse and distorted info.

CLINICO-ANATOMICAL HYPOTHESIS - Emphasizes that dreams begin with arousing stimuli that are generated within the brain combined with recent memories and any info the brain is receiving from the senses.

Homeostasis - temperature regulation and other biological processes that keep body variables within a fixed range.

Set Point - a single value that the body works to maintain.

Negative Feedback - processes that reduce discrepancies from the set point.

Allostasis - The process in which the body achieves stability through changes in its internal env to meet the demands of external stressors and challenges. from Greek root meaning “variable” and “standing” meaning, the adaptive way in which the body changes its set points depending on the situation.

Basal Metabolism - the energy used to maintain a constant body temp while at rest

Ectothermic - depending on external sources for body heat instead of generating it themselves. A synonym is:

Poikilothermic meaning “varied heat”

Endothermic - they generate enough body heat to remain significantly above the temp of the environment

Preoptic Area/Anterior Hypothalamus (POA/AH) - controls the autonomic responses such as shivering, sweating, changes in heart rate and metabolism, and changes in blood flow to the skin. 

Fever - represents an increased set point for body temperature.