CHP9: Importance of sleep AOS1 Flashcards
Circadian rhythm
Changes to our physiological function or activity that occur as part of a cycle that lasts approximately 24 hours.
Sleep
A cyclical progression that is regular and naturally occurring, through which different states are associated with different levels of alertness and psychological responses.
Sleep-wake-cycle
The cycle of going from sleep to being awake within a 24-hour period.
Reversibility
A person can be brought back to a waking state quickly (awoken) with a strong enough stimulus.
Perceptual disengagement
How the sleeper has no awareness of the sensory stimuli in their external environment.
Biological rhythms
Cyclic changes in bodily functions or activities that repeat themselves through time in the same order (e.g. circadian and ultradian rhythms).
REM (rapid eye movement) sleep
A type of sleep where the sleeper experiences rapid eye movement beneath closed eyelids. The sleeper is virtually paralysed therefore most muscle movement is not possible, dreams are frequently recalled if woken during REM sleep, REM is a light stage of sleep as the brain is active and the sleeper can be woken easily.
NREM (non-rapid eye movement) sleep
A type of sleep that is subdivided into four different stages, where the sleeper does not experience any rapid eye movement. Muscle movement is possible for the sleeper, dreams are not frequently recalled when woken during NREM sleep.
NREM1-2 are light sleep and the sleeper may not realise that they have been sleeping if woken during these stages. NREM3-4 are deep sleep and the sleeper is likely to feel drowsy and disorientated if woken during these stages.
Sleep cycle
A proportion of a sleep episode in which the sleeper progresses through stages of REM and NREM sleep, lasting on average 90 minutes for humans.
Sleep episode
The fullest duration of time spent in sleep.
Infradian rhythms
Occur in cycles that last longer than 24 hours (e.g. menstrual cycle).
Describe the function of the suprachiasmatic nucleus (SCN)
Receives information about the amount of incoming light from the eyes and adjusts our sleep-wake-cycle accordingly. It sends neural information to the pineal gland which secretes melatonin into the blood.
Where is the suprachiasmatic nucleus (SCN) found?
Hypothalamus
REM rebound
Catching up on REM sleep immediately following a period of lost REM sleep by spending more time than usual in REM sleep when next asleep.
Evolutionary theory of sleep
A theory that proposes that sleep is adaptive and has evolved to meet specific survival needs.
Restoration theory of sleep
A theory that proposes that sleep replenishes psychological and physiological functioning.
What does the restoration theory of sleep suggest happens during REM sleep?
Replenishes psychological functioning;
Restores adequate neurotransmitter levels;
Maintaining neural pathways through stimulation;
What does the restoration theory of sleep suggest happens during NREM sleep?
Replenishes physiological functioning;
Repairs damaged cells and tissues;
Detoxifies muscles;
Sleep spindles
Brief bursts of higher frequency waves, 2-5 times a minute during stages 1-4 of sleep.
K complex
Sudden sharp waveforms are usually only found during stage 2 of sleep. Triggered by noise and could be also involved in keeping a person asleep.
NREM1 (Hypnogogic state)
Decrease in alpha waves, theta waves prominent. Psychological responses include breathing, heart rate, muscle tension and body temperature declining. NREM1 only lasts 5-10 minutes, sleep is light, and a person can easily be awakened.
This transition period from being awake to being asleep is called the hypnogogic state/ jerk.
NREM2
Mostly theta waves with sleep spindles and K complex appear. Psychological responses include breathing regular, but heart rate, muscle tension and body temperature lowered. NREM2 is a deeper sleep than stage 1 but still easily woken up (e.g. from a loud noise).
NREM3
Long slow delta waves begin to appear. Psychological responses include heart rate, muscle tension and body temperature continuing to be lowered. The sleeper becomes unresponsive to external stimuli, and difficult to wake.
NREM4
Low slow delta waves dominate. Psychological responses include heart rate, muscle tension and body temperature lowered. Muscles are completely relaxed, it is difficult to wake and if woken it takes a long time to orient themselves, and the sleeper may be confused and groggy.
Sleepwalking, sleep terrors, and bed wetting often happens in this stage. Mental activity can occur in this stage in the form of a dream.
Why is REM sleep important?
It replenishes psychological functioning, restores adequate neurotransmitter levels, and helps in maintaining neural pathways through stimulation.
Why is NREM sleep important?
It replenishes physiological functioning, repairs damaged cells and tissues, and detoxifies muscles.
Neonatal (1-15 days)
Require approximately 16 hours of sleep, with 50% REM and 50% NREM sleep proportions. They have irregular sleep-wake cycle, frequent waking during the night and have shorter sleep cycles.
Infant (3-24 months)
Require approximately 13.5 hours of sleep with 35% REM and 65% NREM proportions. They have an irregular sleep-wake cycle (napping), and have lots of facial movement during REM.
During childhood (2-14 years)
Require approximately 11 hours of sleep, with 20% REM and 80% NREM proportions. Additionally they spend more time in NREM 3, and 4.
Adolescence (14-18 years)
Require approximately 8.5 hours of sleep, with 20% REM and 80% NREM proportions. They have delayed sleep onset (1-2hours), are more tired (sleep deprived), and spend less time in NREM 3+4 in later stages.
Adulthood (18-75 years)
Require approximetley 6-8 hours of sleep with 20% REM and 80% NREM proportions. They have an earlier sleep onset, decrease in the number of sleep episodes, and have a gradual loss of NREM stages 3, and 4.
Old age (75+ years)
Require approximately 5-6 hours of sleep with 20% REM and 80% NREM proportions. They experience frequent awakenings and are not getting NREM stages 3, and 4.
