Sleep is a state of mind; during sleep, brain discontinues processing continual sensory information from the 5 basic senses.
Functions? All ideas are currently hypothesis- not thesis.
Hypothesis- educated guess- test construct for gathering information.
Western approach--> reductionist concept, where hypothesis "test" at most two variables to determining key factors.
Idigeonous Science--> global view- observation of how parts work together as opposed to a reduction theory, a continuum, successful hypothesis that leads to theory.
Theory- a statement based on observation and data collected under experimental conditions (controlled environment)
Theories are tested through perdictive experiments and may involve multiple variables. Therefore, if all variables are defined becomes fact.
Indigenous Theories often based on different time scale. Therefore, it is different to test or compare with western theory. As spiritualism is sometimes evoked to account for changes with time. (sleep is an altered state of consciousness)
Sleep is also a complex bhvr. - occurs in mammals and birds -> birds "evolved" from reptiles. But mammals and birds did not evolve from hypothesized ancestors. Sooooo.... Why do birds and mammals share a complex bhvr.?
Study of sleep is important to understanding main function
-evidence suggests that the frontal lobe is "inhibited" at all sleep levels
Approaches to studying sleep-
A) Circadian Cycles and Rhythms
B) EEG and wave patterns
C) Sleep Cycles and autonomic nervous systems (hormones)
A) Circadian Rythms occur in most endoderms daily fluctuation of activity ruled by hormonal influences
The suprachiasmatic nucleus (SCN) contains neurons that keep the clock running
SCN neurons can grow in petri dish (culture) will display rhythmatic activity.
12 hours on/12 hours off (some cultures have days longer than 24 hours) ~the rhythm generators, motor that run the clock.~
But, SCN does not determine period of activity.
Day- Diurnal
Night- Nocturnal
How does the SCN tell time?
3 genes A/B) per, tim (timeless) C) gene clock (circadian locomotor output cycle kaput)
per and tim-> proteins-> inhibit the production of clock protein
But.... per/tim proteins are degraded, eaten by enzymes, at a certain rate (concentration of proteins and enzymes present) When per/tim decrease this allows for expression of clock gene to occure- clock proteins increase. When clock increases it promotes (binds to genes of per/tim to increase proteins.
increase of per/tim then inhibit of clock which stops production of per/tim. (All this cycles back up to where per/tim degraded by enzymes)
SCN keeps time -> SCN regulates/regulated by melatonin ->produced by pineal gland (body) gland-> anything that secretes a hormone.
Melatonin-> synthesized from seratonin which is made from the amino acid tryptophan which is also called indolemine
Melatonin is low during the day and highest in early hours when it's most difficult time to be
awake. M is regulated by light. An increase in light equals a decrease in M, a decrease in light equal and increase in M. M (melatonin) is a sleep inducing hormone.M is a hormone that regulates cells, usually through changing gene transcription.
Hormone help establish if animal is nocturnal or diurnal.
cortisol- wake up
growth - sleep phase
Jet lag -> time or light shift. SCN will adapt with in 48 hours (reticulo hypothalamic) daily rhythm can take up to a week.
Another hormone related to daylight: SAD (seasonal affective disorder) which is a lack of light.
EEG Sleep
A)Discovered pattern of activity that lead to stages of sleep
B) stages of sleep corresponds to different autonomic levels (parasymp= slow, symp=faster)
C) REM occurs in predictable pattern (rapid eye movement moves side to side, not up and down)
NREM--> 4 stages of non REM
1)Theta (θ) rhythms
2) sleep spindles --> K complex
3) δ (delta) rhythms initiate
4) Repetitious δ
Rem--> 1 stage---->β activities (wakeful)
REM-> increase in sympathetic nervous system. Muscle paralysis in REM (fingers/paws), Blocking descending motor pathway recticulo spinotract.
Cycles of sleep--->
A) Require 4 stages of NREM to achieve REM
B)True REM= 90 mins includig sleep cycle
C) After REM, no longer need stages 3-4
Final stage, no 4th
Sleep pattern change across life span
A) Babies need lots of sleep (first 13 days critical for development)
B)Puberty decrease in stage 3-4 NREM and REM. Increasing desire for sleep because without 4 we can't get to REM.
C) Over 40 years, decrease in need for sleep, easier to get REM (See fig. 11.11)
No comments:
Post a Comment