Chapter 13 - Sleep and Dreams Flashcards
biorhythms (biological rhythms)
are cyclical changes in behavior or bodily functions that work as inherent timing mechanism that control or initiate biological processes. each biorhythm has a period
period
time required to complete one cycle
type of biological rhythms
- circannual rhythms
- infradian rhythms
- circadian rhythm
- ultradian rhythms
circannual rhythm
have a year cycle. e.g. hibernation
infradian rhythms
are longer than a day and shorter than a year. e.g. menstrual cycle
circadian rhythm
have daily cycles. e.g. human sleep-wake cycle
ultradian rhythms
have cycles that are shorter than a day. e.g. our eating behavior
endogenous rhythms
controlled internally, by the body itself. this internal mechanism is called a biological clock
exogenous rhythm
are controlled externally, for example, by the sun or seasons. you can know whether a rhythm is exogenous or endogenous by keeping the external conditions constant
free running rhythm
is a rhythm of the body’s own devising, in the absence of all external cues
zeitgebers (time givers)
environmental events or cues that determine or modify biological rhythms. the effect of zeitgebers on biological rhythms is called entrainment
jet lag
occurs because the zeitgeber (light) is not synchronized with the biological clock. we have more trouble adjusting traveling from west to east than from east to west
superchiasmatic nucleus (SCN)
main biological clock structure. a part of the hypothalamus. consists of two parts: a core and a shell. the SCN does not cause any behavior itself. the SCN’s pacemaker cells entrain the slave cells oscillators
pituitary gland
this is activated in daylight and stimulates the adrenal glands, which release cortisol. cortisol supports arousal activities in the sympathetic system
2 important oscillators
- pineal gland
- pituitary gland
pineal gland
activated in darkness and releases melatonin, which activates the parasympathetic rest-and-digest system. melatonin plays a role in the circadian sleep-wake cycle in humans, and in circannual cycles in animals
body signals and ways for measuring sleep
- eye movements = electro oculogram (EOG)
- muscle activity = electromyogram (EMG)
- brain activity = electroencephalogram (EEG)
sleep stages (types of brain waves)
based on the analysis of EEG, which measures the amplitude and height of brain waves. based on EEG there are five different brain wave types
five states of consciousness based on EEG
- W-Waking
- N1-NREM stage 1
- N2-NREM stage 2
- N3-NREM stage 3
- R-REM
W-Waking
a state that goes from alert to wakefulness to relaxation and drowsiness. it includes beta waves (open eyes) and alpha waves (closed eyes)
N1-NREM stage 1
is the onset of sleep, and it includes theta waves
N2-NREM stage 2
is a state of theta-wave sleep, in which there are sleep spindles and K-complexes. sleep spindles are bursts of activity associated with explicit learning. K-complexes are related to environmental stimuli
N3-NREM stage 3
in deep sleep, involving delta waves
R-REM
a state of sleep in which dreaming occurs, and it involves beta and theta waves, so it resembles the waves of both waking and NREM stage 1.
distinction between REM sleep and NREM sleep
after NREM stage 3, brain moves into REM sleep. brain waves become faster, EEG frequency increases and EMD shows atonia. atonia is the result of inhibitory signals sent from the brainstem to motor neurons in the spinal cord that command movement. furthermore, EOG shows horizontal rapid eye movement and there may be twitching
hypnogram
used to graph sleep stages for a night
REM-rebound
having to catch up on REM sleep after not sleeping or sleeping very little
dreaming
happens mainly during REM sleep. if you wake people up during REM sleep, 80% tell a vivid dream
Freud on dreams
stated that they were unconscious wishes
activation-synthesis theory
states that dream are a by-product of random brain activity
coping theory
states that dreams are biologically adaptive and make it easier to deal with dangerous situations
continuation theory
states that the problem-solving activities in which we are occupied during the day continue during sleep in the form of dreams
what does sleep accomplish?
- sleep as a biological adaptation process
- sleep as a recovery process
- sleep as supportive memory
sleep as a biological adaptation process
sleep can be considered as biologically adaptive behaviour influenced by the way species are developing to interact with the environment
sleep as a recovery process
body recovery: e.g. more growth hormone during NREM sleep
brain recovery: waste products are cleaned up
sleep as a supportive memory
important events that occurred during the day are “played back’ during NREM sleep and stored in long-term memory. in humans, implicit memory is consolidated during REM sleep
reticular activating system (RAS)
responsible for sleep-waking behavior. inhibition of RAS produces an asleep EEG pattern. stimulation of RAS produces an awake EEG pattern
insomnia (NREM sleep disorder)
the inability to fall asleep or stay asleep
hypersomnia (NREM sleep disorder)
difficulty is waking up or staying awake
narcolepsy (REM sleep disorder)
a condition in which people suddenly fall asleep during unwanted times and places, going directly to REM sleep
cataplexy (REM sleep disorder)
a sudden loss of muscle tone that occurs during wakefulness. it is triggered by excitement or laughter
sleep paralysis (REM sleep disorder)
occurs when people wake up while REM sleep is either starting or ending, so that muscles are still completely relaxed
