chapter 13 - sleep Flashcards
biorhythm
timing mechanism that controls biological processes
- linked to cycle of days and seasons produced by Earth’s rotation around sun
circadian rhythm
daily rhythm of daylight activity and nocturnal sleep that dominates human behaviour
endogenous:
control comes from within
biological clock:
neural system that times behaviour by synchronizing it to the temporal passage of the real day
*animals can anticipate events
what does the biological clock regulate (4)?
- feeding times
- sleeping times
- metabolic expression
- gene expression
period:
time required to complete a cycle of activity
circannual rhythm
yearly
infradian rhythm
less than a year
ultradian rhythm
less than a day
free-running rhythms:
rhythm of body in absence of all external cues
- periods of 25-27 hours
w/ free-running rhythms, how much does the sleep cycle shift each day?
about an hour
how long are nocturnal free-running rhythms in constant dark? light?
constant darkness = shorter than 24 hours
constant light = longer than 24 hours
how long are diurnal free-running rhythms in constant dark? light?
constant darkness = longer than 24 hours
constant light = shorter than 24 hours
zeitgeber:
time setter - environmental event that determines/ maintain period of biorhythms
what does an “entrained” biological clock allow us to do?
synchronize daily activities across seasonal changes
2 things that disrupt our biorhythms:
- light pollution
- jet lag
what role does the SCN plat in circadian rhythms?
main pacemaker
*above optic chiasm
5 pieces of evidence for SCN’s role:
- if damaged, daily activities lack normal organization
- SCN cells increase metabolic activity during light period
- cells are more electrically active during light period
- SCN neurons maintain rhythmic activity in absence of in/output
- cells in a dish retain periodic rhythm
melanopsin
photosensitive pigment in RGC’s - respond to blue light
retinohypothalamic path:
- retina
- retinohypothalamic tract
- optic chiams
- SCN
2 SCN subdivisions:
- core (ventral) = non rhythmic
- shell (dorsal) = rhythmic
what are the 2 groups of circadian neurons? functions?
m cells = require light, control morning activity
e cells = require darkness, control evening activity
are SCN endogenous rhythm’s learned?
no - animals still exhibit rhythmic behaviour
what does the SCN pacemaker drive?
slave oscillators
slave oscillators:
control rhythmic occurrence of one behaviour
ex: motor activity, eating, body temp
melatonin:
promotes sleep, influences rest and digest system (PNS)
where is melatonin released from?
pineal gland - circulates during dark phase
*inhibited in spring, activated in winter
where are glucocorticoids released from?
adrenal glands - circulate during light phase
glucocorticoids:
mobilize glucose for cellular activity - support arousal responses in SNS
beta waves:
when?
type?
- waking state
- small amplitude, fast frequency
alpha rhythm:
when?
type?
- relaxed state
- larger amplitude, slower frequency
what is N1 sleep? what waves do we see?
- drowsy state, sleep onset
- theta, mixed waves
what is N2 sleep? wave type?
- asleep
- stable theta waves
*occasional sleep spindles and K-complexes
what is N3 sleep? wave type?
- deep sleep
- delta waves (large amplitude, slow frequency)
what is REM sleep? wave type?
- dreaming
- beta waves
- atonia
how long are periods of sleep states? how many/ night?
- 90 minutes
- 5/ night
what occurs in body during NREM sleep?
- decrease body temp, HR, blood flow, BW
- increase in growth hormones
- maintain muscle posture
- less vivid dreams
what occurs in the body during REM sleep?
- regulatory mechanisms stop
- atonia = motor neurons inhibited, some twitches
Freud’s theory of what dreams are?
symbolic fulfillment of unconscious wishes
Jung’s theory of what dreams are?
expressions of our collective unconscious
what are most dreams we have related to?
recent events and concern ongoing problems
bottom up dream interpretation: activation synthesis
- dreams are meaningless brain activity
- cortex generates images from personal memory
top down dream interpretation: coping hypothesis
- dreams lead to adaptive performance when dealing w threatening events
- problem solving - “sleep on it”
when does sleep paralysis typically occur?
when stressed out
how does lucid dreaming differ?
- you’re in control
- positive, coping
what can promote lucid dreaming?
ACh agonists
how is sleep a biological adaptation?
- energy -conserving strategy
- animals w/ nutrient rich diets spend more time sleeping
- can’t see well at night = sleep
BRAC - basic rest activity cycle
- recurring cycle of temporal pockets ( ~90 min in humans) where animal’s level of arousal waxes and wanes
what are the restorative properties of sleep?
- chemical events that provide energy to cells may be reduced during waking, are replenished during sleep
3 phases of memory storage:
- encoding
- consolidation
- recall
encoding aka labile phase
new memory encoded
consolidation phase
relatively permanent representation of memory solidified
recall phase
neural networks that represent memory are activated
multiple process theories
different kinds of memory are stored during different sleep states
sequential process theories
memory is manipulated in different ways during sleep states
storage process theories
brain regions that handle different kinds of memory during waking continue to do so during sleep
