Chapter 15 Flashcards
Sleep
partially conscious and unconscious
Restorative Function
species with higher metabolic rates sleep more
Adaptive Hypothesis
amount of sleep an animal engages in depends on the availability of food and on safety consideration
Circadian Rhythms
- ‘about day’
-entertained by environmental cues
Suprachiasmatic Nucleus (SCN)
region of the hypothalamus; acts as the main biological clock
- connected to the sun
- regulates sleep
- signals the pineal gland to release melatonin
Endogenous Rhythms
rhythms from within the body
Melatonin
hormone that induces sleepiness
- SCN controls the production of melatonin
- light resets the biological clock every day by suppressing melatonin secretion
Pineal Gland
releases melatonin when signalled by the SCN
Ultradian Rhythms
rhythms less than a day in length
- hormone production, unitary output, alertness
- basic rest and activity cycle is a rhythm that is about 90-100 minutes long
Stage 1 Sleep
transition to light sleep (1-10 mins)
- alpha/beta waves from wakefulness transition to theta waves when you have fallen asleep
- hypnic/ myoclonin jerks and hypnagogic imagery
EEG
used to measure sleep
Beta Waves
awake/alert
Alpha Waves
relaxed/drowsy
- bigger than beta waves
Theta Waves
stage 1
- less frequent that alpha waves
Stage 2
deeper sleep (10-25 mins)
- brain waves decelerate, heart rate slows, body temperature decreases, muscles relax, eye movements cease
Sleep Spindles
1-2 seconds of rapid brain activity
K-complexes
neural excitation followed by neural inhibition
Stage 3 and 4 (~30mins)
Slow Wave Sleep
appearance of delta waves
- important to feel rested
- only difference between 3 and 4 is the height and the frequency of the delta waves
REM Sleep
waves most similar to beta waves
- occupies 20-25% of our nights sleep
- cycles of REM sleep last between 20min-1hr
- pulse becomes irregular, breathing increase, muscles stop working
- dream the most and most vivid story like dreams
- children spend more time in REM than adults, 50%
Hypothesis 1
sleep has evolved to conserve organisms energy
- evidence is strongest for this hypothesis
Hypothesis 2
immobilization during sleep is adaptive because it reduces danger
Hypothesis 3
sleep helps animals to restore energy and other bodily resources
Functions of Slow-Wave Sleep
restoration of the brain
- sleep deprivation produces cognitive deficits
Sleep, Plasticity, and Memory
REM sleep important part of memory consolidation; learning and memory
- REM sleep deprivation after learning reduces retention
- period of consolidation followed by clean up
- larger flow of CSB; controlled by glial cells that are transporting the CSB
Brain Structures involved in Sleep
use more brain energy during slow wave sleep
- no single sleep or waking centre
- integrate with the SCN and it’s circadian rhythm
Brain Stem Arousal Centre’s
send activating signals to shier level fo the brain
PPT and LDT
fire most rapidly during wakefulness and REM sleep; most slowly during non-REM sleep
- driving cortical activation outside non-REM sleep
Second Branch; Basil Forebrain
locus coeruleus, raphe nuclei, tuber-mammillary nucleus, and parabrachail nucleus
Orexin
released by the lateral hypothalamus and it keeps us awake
Ventrolateral Preoptic Nucleus (VLPO)
located in the hypothalamus
- neurons inhibit arousal networks
- neurons fire 2-4 times faster during non-REM sleep and still more as sleep deepens
inhibits the PPT/LDT
Parafacial Zone
in the medulla
- possible involved but not enough research yet
PGO Waves
high-voltage brain waves that travel from the pons through the lateral geniculate nucleus of the thalamus to the occipital area
- begin 80 seconds before start of REM period
- initiate the EEG desynchrony of REM sleep
Sublaterodorsal Nucleus
found in the pons
- governs switching in and out of REM sleep
- believed to be the most important area for REM sleep
Insomnia
inability to sleep or to obtain adequate-quality sleep, to the extent that the person feels inadequately rested
- not able to get enough stages 3 and 4 sleep
- chronic
- most common sleep disorder
- stress, poor sleep hygiene, withdrawal from depressants, reliance on sleep aids but stopped using them
- depression and anxiety;
Sleepwalking
originates during deep sleep and results in walking or performing other complex behaviours while still mostly asleep
- triggered by stress, alcohol, and sleep deprivation
- genetic component
Narcolepsy
disorder in which individuals fall asleep suddenly during daytime and go directly into REM sleep
- at nighttime, they sleep just like everyone else
- usually deficient in orexin but normal levels of melatonin
Cataplexy
disorder in which the person has a sudden experience of one component of REM sleep, atonia, and falls to the paralyzed but fully awake
- can come hand in hand with narcolepsy
REM sleep behaviour disorder
affected individuals are uncharacteristically physically active during REM sleep, often to the point of injuring themselves or their bed partners
- more common in men because more common in people who drink and smoke heavily, work in welding and pesticides
- within ten years of diagnosis, individuals will develop Parkinson’s
