Lecture 5: Sleep Flashcards
Sleep, general functions
- white blood cell production
- improves memory consolidation
- cleans out plaque from brain
• increased level of growth hormone
o more sleep as needed for infants and adolescents
• decreased need for sleep in the elderly
Resetting our sensory buffers
o “flush out the system to a neutral place”
o bedroom – neutral, lacking in stimuli
Evolutionary
o diurnal – we are built for the daytime, the brain shuts the body down at night
o seasonal affect disorder
o fatigue/depression in winter with less daylight
Circadian Rhythm
Retinal cells reflect to superchiasmatic nucleus, a region of the hypothalamus which releases melatonin in absence of light
• seasonal affective disorder lightbox is designed to prevent the release of melatonin
*circadian rhythm is not perfectly linked to 24 hour cycle
Ultradian Rhythm
An ultradian rhythm is a recurrent period or cycle repeated throughout a 24-hour circadian day
o e.g., are blood circulation, blinking, pulse, hormonal release, heart rate, appetite
Infradian Rhythm
Infradian rhythms have a cycle of longer than one day.
Examples include the menstrual cycle, and bipolar, major depressive, and seasonal affective disorders.
o often springtime sees a spike in depression, suicidality
**good weather contrasts with mood, heightens sense of social isolation
Waking Brainwaves
gamma–active cognition, binding representations
beta – awake and alert
alpha – awake and relaxed—drowsy
Sleep Cycle: Stage 1
o theta waves 1-3cps
o 1~8 minutes
o 5% of sleep
o still retain muscle tone
o hypnogogic hallucinations
Sleep Cycle: Stage 2
o 2-14 cps
o lasts 15-20 minutes
o 45% of sleep
o Sleep spindles [groups high frequency waves]
• usually caused by noise
o K Complex–large spike
• usually caused by tactile/physical stimuli
Sleep Cycle: Stage 3
o Delta waves, ½—2 cps [SWS: Slow Wave Sleep]
o Stage 3 Early
• 5% of sleep
o Stage 3 Late
• 15% of sleep
- muscle relaxation, snoring
- mentalis muscle – only becomes slack during sleep, no waking conscious control of relaxation possible
- nightmares/night terrors
- different than bad dreams– sense of panic
- if someone can describe a dream, it is most likely a bad dream, as nightmares are not easily remembered
- sleepwalking/sleep talking
- very groggy waking up from Stage 3 sleep
- when taking naps, it’s best to sleep for 20 minutes or 90 minutes
- don’t want to wake up from stage 3, ok to wake up from stage 2 or REM, less work to return to wakeful alert state
REM
REM
• differs from SWS, more closely resembles Stage 1 sleep
o low-voltage – random, fast with sawtooth waves
- REM is its own stage, but kind of replaces Stage 1
- EEG shows that REM is similar to consciousness
- heart rate and respiration increase, but there is a complete loss of muscle tone
- dreams generally refer to stimulation experienced during the previous day
- wake up from REM, don’t feel too groggy
- awakenings help remember dreams
o theory behind the function of the movement of the eyes during REM sleep
• possibly syncing the two hemispheres
• consolidation & coordination
o treatment of PTSD
• drugs that disrupt memory consolidation
REM deprivation
REM deprivation o memory limitation o concentration difficulties o increased appetite o anxiety
REM deprivation is really more annoying than devastating
o compensation does not work on a 1:1 ratio
• one hour of deprivation may only need 10 extra minutes of REM sleep
Ventral Lateral Pre-Optic Area [hypothalamus]
starting point for Slow Wave Sleep (SWS)
suppresses cortical activity
inhibits acetylcholinergic neurons to help with muscle relaxation
Locus Coeruleus
(Neuroanatomical Correlate of REM Sleep)
Releases norepinephrine
slightly increase alertness
Peribracheal Area
(Neuroanatomical Correlate of REM Sleep)
o superior colliculus –eye movement
o inhibits motor neurons for lack of muscle tone (atonia)
Reticular Formation
(Neuroanatomical Correlate of REM Sleep)
o Alterness, arousal
o damage to the reticular formation results in chronic sleep
Narcolepsy
- straight into SWS or REM
- can occur at any time of day
• usually occurs when there is a lack of stimulation
o e.g., repetitive tasks, movie, etc → boredom
etiology: degradation of hypocretin neurons, which seem to suppress the switch into REM
functional as it is better to have the body relaxed –atonia before REM
• produces a “faulty switch”→striaght into REM
