reversed definitions ch 14

somnambulism

sleepwalking

circadian rythm

a biological rhythm of about 24 hours

sleep paralysis

inability to move or speak, sometimes accompanied by hallucinations, experienced by narcoleptics at sleep onset

nocturnal

active at night (with regard to animals)

diurnal

active during the day (with regard to animals)

sleep-onset insomnia

sleep disorder characterised by difficulties in falling asleep

period

the length of time between two occurrences of a rhythmic event

reticular formation

diffuse network of cells extending from the medulla to the midbrain, implicated in arousal

phase shift

the shift in rhythms induced by the appearance of a synchronising stimulus

entrainment

process of synchronising a rhythm to a particular stimulus (such as light)

nightmare

frightening dream that causes arousal from REM sleep

zeitgeber

a stimulus that entrains rhythms, usually light

suprachiasmatic nucleus

hypothalamic region that has been demonstrated to contain an important endogenous circadian clock

sleep-maintenance insomnia

Sleep disorder in which there is difficulty in staying asleep

sleep cycle

the period of time that includes one bout of SWS and one bout of REM sleep

sleep enuresis

Formal name for bedwetting

sleep recovery

General name for the process of repaying missed sleep

night terror

frightening dreamlike state that wakens sleepers from stages 3 and 4 SWS

cataplexy

sudden loss of muscle tone, leading to collapse of the body without loss of consciousness

pineal gland

gland that secretes melatonin, located in the midline of the brain

retinohypothalamic pathway

Fiber tract that conveys light information from the eyes to the SCN

ultradian rhythm

General term for a biological rhythm with a period less than 24 hours

circannual rhythm

General term for a biological rhythm with a period of about 365 days

infradian rhythm

general term for a biological rhythm with a period of more than 24 hours

EEG

technique in which scalp electrodes are used to record the electrical activity of the underlying brain

narcolepsy

disorder characterised by bouts of sudden, intense sleepiness

basal forebrain

diffuse region including the basal ganglia, implicated in the generation of slow-wave sleep

sudden infant death syndrome

lethal form of sleep apnea that affects infants

EMG

technique in which electrodes are used to record the electrical activity of muscles

REM sleep

sleep stage during which the majority of dreams occur

alpha rhythm

Characteristic EEG component of people that are resting and relaxed, with their eyes closed

sleep spindles

periodic bursts of 12-14 Hz waves that are seen in the EEGs of people in stage 2 SWS

delta waves

very large amplitude, very slow waves that occur during stages 3 and 4 SWS

sleep apnea

slowing or cessation of respiration during sleeping that results in decreased blood oxygen, arousal, and daytime sleepiness due to sleep interruptions