NEW335H1 Lecture Notes - Lecture 10: Slow-Wave Sleep, Sleep Spindle, Rapid Eye Movement Sleep
Lecture 10 –meditation on sleep
Why is sleep important?
•Maintenance of the brain (clearance of waste)
•Restoration of injured/damaged tissue
•Ontogenetic development of the brain ! growth and brain, maturation of
behaviour and reasoning occurs during sleep (cannot occur while awake)
•Maintenance of learning + memory processes ! memories acquired during
awake are being consolidated for LT maintenance (memory loss without sleep)
What are the 5 stages of sleep?
•5 stages: one stage of rapid eye movement (REM) and several stages of NREM
sleep (NREM 1-4)
•Each sleep stage may serve a relatively unique function ex: slow wave sleep –
consequences for learning, cognitive and memory?
•Stage N1 (Light) Stage N2 Stage N3-4 (Deep)
On the EEG, what frequency ranges are typically observed in different sleep
stages? When are events such as spindles and K complexes observed?
NOTE: Beta: >13 Hz, Alpha: 7-13 Hz, Theta: 4-7 Hz, Delta: 1-4 Hz
•NREM1 (Light Sleep): Slightly lower frequency activity (Alpha + Theta waves,
4-7 Hz)
•NREM2: Lower frequency activity (theta, 4-7 Hz) with sleep spindles and K-
complexes
•NREM3/4 (Deep Sleep or Slow Wave Sleep): Mostly very low frequency activity
(delta, 1-4 Hz) and some spindles
•REM (Dream stage): High frequency activity, similar to that seen in eyes-open
wakefulness ! very fast, comparable to a waking phase
•Beta range when you’re up and alert, the more you relax slower the activity
gets (alpha)
•NOTE: NREM 2 ! spindles and K complexes, NREM3/4 ! some spindles
Explain sleep stage cycling
•In a normal period of sleep, we cycle between stages (REM, NREM 1-4).
•Here, the REM stage of sleep is labelled in red.
•The amount of time we spend in each sleep stage is different. Note the
relatively short REM time
•older you get, less REM you have!
•These stages of sleep may each serve relatively unique functions and be
differentially affected by drugs and treatments such as meditation
How is sleep affected by aging?
•REM sleep decreases with age! function of REM impaired (memory/cognition)
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•Babies have lots of REM sleep (~50% of total sleep) relative to normal adults
(~20% of total sleep)
•In the elderly (>65 years), the REM sleep period is even shorter
Sleep disturbances are common in elderly individuals, often occurring in connection
with other medical problems
•50% of older adults report some form of sleep disturbance
- Many not formally diagnosed or treated
•In elderly adults, several changes in sleep are commonly observed:
1) Sleep onset is delayed (longer sleep latency)
2) Deep sleep (NREM3,4 and REM sleep periods) are shortened
3) Awakenings (periods of arousal) are more common
Note in graph: older ! so many interruptions of arousal/awakening ! a lot less REM
and
Differentiating
primary and secondary insomnia
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Document Summary
Stage n1 (light) stage n2 stage n3-4 (deep) Note: beta: >13 hz, alpha: 7-13 hz, theta: 4-7 hz, delta: 1-4 hz: nrem1 (light sleep): slightly lower frequency activity (alpha + theta waves, In a normal period of sleep, we cycle between stages (rem, nrem 1-4): here, the rem stage of sleep is labelled in red, the amount of time we spend in each sleep stage is different. Note the relatively short rem time: older you get, less rem you have, these stages of sleep may each serve relatively unique functions and be differentially affected by drugs and treatments such as meditation. How is sleep affected by aging: rem sleep decreases with age! function of rem impaired (memory/cognition, babies have lots of rem sleep (~50% of total sleep) relative to normal adults (~20% of total sleep) In the elderly (>65 years), the rem sleep period is even shorter.
