What is sleep? (2)
-is characterized by the absence of behavior.
-during sleep, there is a higher threshold for arousal by external stimuli
Who contributed to sleep research?
-NAthaniel Kleitman from U of C
*used his graduate students as testers
(types of recordings) What is Electroencephalography (EEG) ?
- -averages the activity of hundreds to thousands of individual neurons.
- *similar to recording the activity of individual neurons like we've seen in vision lectures
(types of recordings) What is Electro-oculography (EOG)?
-recordings of eye movement
(types of recordings) What is Electromyography (EMG)?
-recordings of muscle tension
Which two major classes of sleep have been descoverred?
-slow-wave sleep and
-Rapid-eye movement (REM) sleep
Description of beta activity
- -low amplitude, high frequency activity
- *15-20 HZ
-awake and alert
Description of alpha acitivty (2)
- -relaxed conditions, with eyes closed
- *also stage 1 and 2
- -activity becomes more synchronized and a distinct rhythm emerges
- *8-12 HZ
(stages of sleep) Stage 1- 6 characteristics
-alpha rhythm (8-12 hz)
-EEG shows smaller amplitude and irregular frequency
- -occasional sharp waves
- *vertical spikes
-slower heart rate, reduced muscle tension
- -eyes start to roll about slowly
- *last several minutes before they enter 2nd stage
(stages of sleep) Stage 2 (3)
- -characterized by the occasional appearences of high frequency EEG
- *sleep spindles
- *k complex
- **alpha rhythm interupted ocassionaly by these two
-when people wake up from stage 1 or 2, they often do not acknowlege that they have been sleeping
(stages of sleep) Stage 3
- -delta waves start to appear
- *have a frequency of 1 hz
(progression of stages) during first hour of sleep there is an orderly...
progression through SWS stages
progression steps through stages
- 1. first stage then goes in numerical order to 4, then back to one
- *once it starts over to one, it shows different EEG patterns than initial stage 1
- **referred to as emergent stage, EEG
2. after the second turn through stages, after first stage, REM stage will appear
(REM) Characteristics of REM stage
-EEG pattern resembles that of an awake state
-EMG recordings show muscles are completely flaccid (relaxed)
-irregular breathing, and pulse rate
-vivid dreams occur during REM
-rapid eye movements under the eyelids
(sleep walking) Somnambulism
- -widely believed to occur during REM and dreaming
- *not true
-sleep walking and talking occur most often during state 4SWS
MOst mammals as well as birds exhibit periods of...
- SWS and REM sleep
- *exceptions are echidna and dolphin
- **REM and SWS developed more than 150 years
Dol[hins and whales and SWS and REM
-theymust deciede when to come up for air
-they solve this problem by permitting one side of sleep to sleep at a time
sleep duration is linked to metabolism
animals with high metabolic rates have short sleep cycles abd animals with low metabolic rates have long sleep cycles
sleep cycles typically last from...
*in rats: 10-11
what age do sleep patterns rise?
until 16 weeks of age
REm levels rise from...
- infants to elderly
sleep patterns as we age
-less REM sleep
-more waking episodes
- -dramatic reduction in stage 3 and 4
- *which correlates with reduced cognitive abilities and senile dementia
How was the role of hypothalamus discovered in sleeping?
-investigating sleep disorder narcolepsy
NArcolepsy characteristics (4)
-last anywhere between 5 to 30 mins
-can occur anytime during wake hours
-con occur every 90 mins
-1 of every 2000 americans suffer narcolepsy
hallmarks of narcolepsy
-manifests between ages of 15 and 25
-they enter REM within few minutes of falling asleep
-exhibit normal sleep patterns at night
-accmpanied by cataplex
-sudden loss of muscle tone leading to collapse of body eithout a loss of consciousness
- -can be triggered by strong emotional triggers
HYpocretin and narcolepsy
-mutation in genes might be responsible
ex)mice that lacked hypocretin displayed narcolepsy
ex) normal rats can be made narcoleptic when ejected toxin that attacks hypocretin
Humans that exhibit narcolepsy have lost..
90% of their hypocretin neurons
hypocretin is responsible for...
preventing sleep and the transition from wakefulness to REM
where is hypocretin made and releaseed?
(hypothalamus and hypocretin) cell bodies of neurons project to other 3 regions involved in sleep
- reticualr formation
Sleep paralysis characteritics
- temporarily inaility to move or talk either just beofre falling asleep or just after waking up
- *last few minutes
what causes sleep paralysis?
-pontine nuclei continuing to impose paralysis when one is awoken from REM
-inability to fall asleep or remain asleep
-15-30 % of adult population
sleep onset insomnia
-time zone changes
- -environmental conditions
- *sleeping in new place
-trouble remaining asleep
-typically go hand in hand with respiratory disorders such as sleep apnea
- person stops breathing several times a night
- *results from tongue and throat blocking airways from atonia
- *could be due to CNS failing to stimulate breathing