Sleep Flashcards
what are the two main theories for why we sleep
- restoration/recuperation theories
- circadian theories
what does the restoration theory of sleep propose
sleep restores homeostasis and supports brain plasticity
what does the circadian theory of sleep suggest
sleep is needed for internal timing and evolutionary adaptation to protect us during night time
how much of our lifetime do we spend sleeping
around 170,000 hours, or around 20 years.
what does circadian mean
circa = about, diem = day. a biological rhythm of about 24 hours
what is a zeitgeber
an environmental cue (like light) that helps entrain circadian rhythm
what does entrainment mean
control the timing of
what happens to circadian rhythms without zeitgebers
people experience a free-running cycle, often slightly longer than 24 hours
what hormone is secreted at around 21:00 to help regulate sleep
melatonin
what did Wright et al. (2013) - camping vs. normal environment study show
biological clocks resynchronise to natural light
how does artificial light affect sleep
it delays circadian timing and effects melatonin secretion
what is jet lag
sleep disruption due to crossing time zones and change in zeitgebers
which is harder: eastward or westward travel?
eastward (phase advance)
why is westward travel easier than eastward
because its easier to stay up later than to fall asleep easier
how does shift work disrupt sleep
zeitgebers remain constant, but work hours shift. sleep is shorter if during the day
health risks of shift work and jet lag
- diabetes
- depression
- obesity
- cancer
what are the 4 stages of sleep
stage 1
stage 2
stage 3
stage 4 (non-rem)
followed by REM
what is slow wave sleep
stages 3 and 4 - deep sleep with delta waves
what are alpha waves associated with
relaxed wakefulness
freq of alpha waves
8-12Hz
what are beta waves
low amplitude, high frequency waves during alert wakefulness
freq of beta waves
13-30Hz
what characterises stage 2
sleep spindles and k complexes
what are PGO waves
bursts from the pons to the LGN and occipital cortex during REM
what are 3 consistent effects of sleep deprivation
increased sleepiness, mood disturbance, poor vigilance performance
what are micro sleeps
brief episodes (2-3 seconds) of sleep while awake
how long did Randy Gardner stay awake in (1965)
11 days
what is insomnia
difficulty falling asleep or staying asleep
what is sleep apnea
interrupted breathing during sleep, often airway obstruction
what is narcolepsy
sudden sleep attacks during the day; includes cataplexy, sleep paralysis, and hallucinations
what neurotransmitter is lacking in narcolepsy
orexin (hypocretin)
what is manifest content
actual dream content
what is latent content
hidden, unconscious meaning
what is the activation synthesis theory of dreaming
dreams are the cortex’s attempt to make sense of random brainstem activity (Hobson and McCarley, 1977)
what happens in REM rebound
increased REM after deprivation
what % of participants report vivid dreams during REM (dement and kleitman, 1957)
80%
what structure is key for regulating circadian rhythms
suprachiiasmatic nucleus (SCN) of the hypothalamus
what hormone is secreted by the pineal gland to induce sleepiness
melatonin
what is ARAS
ascending reticular activating system - controls wakefulness
what did von economo discover would happen as a result of damage to anterior hypothalamus
insomnia
what would happen as a result of damage to posterior hypothalamus
hypersonia
what is the passive theory of sleep
sleep occurs due to reduced sensory input (Bremner, 1937)
what did EEG studies show in cerveau isole preparation
continuous slow wave sleep
what happens at 9pm in circadian rhythm
melatonin secretion starts
what time is deepest sleep circadian rhythm
2am
what time is body temp lowest in sleep
4:30am
what time does the sharpest BP rise happen
6:45am
what time does melatonin secretion stop
7:30am
what happens at 10am circadian rhythm
highest alertness
what time do we have the best coordination
2:30pm
what time do we have the fastest reaction time
3:30pm
what time are we the strongest in the day
5pm
what happens at 6:30pm circadian rhythm
highest BP
what time do we have the highest body temp
7pm
what does EEG measure
brainwave activity near the electrodes
what does EOG measure
eye movements
what does EMG measure
muscle activity (commonly in the neck)
someone travels eastbound and goes to bed at 10pm and wakes up at 6am, but this feels like?:
feels earlier - like going to bed at 7pm and waking up at 3am
what are sleep spindles
brief bursts of 12-14Hz waves in stage 2 sleep
what are K complexes
sharp, high amp waves in stage 2, in response to stimuli
what is the frequency of delta waves
0.5-4Hz (very slow, deep sleep waves in stage 3-4)
what is cataplexy
sudden muscle weakness during wakefulness
what does EEG stand for
Electroencephalogram — brain activity
what does EOG stand for?
Electrooculogram — eye movement
what does EMG stand for
Electromyogram — muscle activity
