Eating, sex, and other needs Lecture 4: Sleep

HC4 Sleep

 More than 80% of students wake up feeling tired and unrefreshed
 General population: about 25%

Sleep
 A “lack of waking”? (Aristotle)
 Naturally recurring state of mind and body, in which:
o The senser are inhibited
o Muscles are relaxed
o Heart rate, blood pressure, and body temperature decrease
o Metabolism slows down
o There is no consciousness... but the brain is active
o Biological need

Sleep cycle
 There are five stages of sleep
 We can measure them using
EEG of EOG
o EEG: measuring
electrical patterns of
brain waves. These
brain waves vary
from high amplitude
and low frequency
(relaxation) to low
amplitude and high
frequency (arousal)

Five stages of sleep
0. Awake (5%)
1. Transition (2-5%)
2. Light sleep (45-55%)
3. Start deep sleep (3-8%)
4. Deep sleep (15-20%)
5. Dream sleep (20-25%)

REM = fase 5. NON-REM = 1 t/m 4
REM = rapid eye movements

, Stage 0:
 You feel drowsy
 You yawn, our eyes are closing
 Alpha waves

Stage 1: transition
 Transition from being awake to being asleep
 Your consciousness drifts away
 Your heartbeat slows down
 Your breathing slows down
 Alfa-waves with occasional theta waves

Stage 2:
 Light sleep
 Your temperature drops
 Your breathing slows down
 Your heartrate slows down
 Your muscles relax
 Theta waves + beginning of
delta waves
 Sleep spindles: short burst of
neural oscillation
 K-complex; largest event in
healthy human EEG
 Two functions:
o Suppressing cortical
arousal in response to external stimuli. Imagine you’re asleep and there are some
kind of external stimuli (a noise), that causes activation in the cortex. These two
phenomena help to decrease or suppress that arousal.
o Aiding sleep-based memory consolidation.