Sleep-Wake disorders- exam 3 Flashcards
What is the etymology of the word circadian
Latin: ‘crica’ and ‘diem’ means ‘about a day’
why do organisms have intrinsic time-keeping systems
- Synchronize our body functions
- many mammalian cells, organs, & tissues have rhythmic activity
- synchronize across tissues, organs, and the body for optimal functioning
- in mammals, 5-10% of the genome is rhymically transcribewd (many at night)
why do we match behaviors to the light/dark cycle of the planet
Active under optimal conditions (light)
Inactive: when moving about would be dangerous (dark):
- conserving energy
- restoring brain glycogen stores
- producing protiens and building up tissues
- secreting growth hormones and gonadotropins
- memory consolidation
why must we adjust the intrinsic time-keeping system (why is not set for a standard 24 hour cycle)
in humans the free running clock is 24.5 hours. The light must shift the animal’s clock each day by an amount equal to the difference between their intrinsic free-running period and the 24-hour period of the lighting cycle
what signal adjusts our time keeping system
retinal detection of light via melanoplasin in speical retinal ganglion cells (M1 ganglion cells)
what is the intrinsic period of the ‘free-running’ circadian oscillator for humans
24.5 hours
what is the specific brain structure of the mammalian circadian timing system and in what larger brain system is it located
The suprachiasmatic Nucleus: a pair of small brain structures in the anterior hypothalamus just above the point where the optic nerves cross
what type of cell in the retinal is responsible for adjusting our 24 hour circadian rhythym. What type of light does it respond to and where does it project?
M1 ganglion cell- responds to blue light
what substance does the pineal gland secreate at night
melatonin
what are the two main neurochemicals involved in the sleep/wake cycle
Orexin and GABA
what are the 2 systems that regulate sleep
Circadian time and Homeostatic pressure
when does our circadian rhthym cause us to sleep
it is a sleep independent process- it is tied to time of day.
provides:
- day time awake signal
- nighttime decrease activity and sleep signal
- post-prandial sleepiness- after meals
what causes the homeostatic system to make us sleep
sleep propensity or sleep need
- becomes higher as a person remains awake for longer
- while we are awake adenosine levels rise.
- increasing sleep deprivation results in higher brain concentrations of adenosine
- a person who sleep deprived requires extra sleeping time for sleep prpensity to dissipate
what chemical builds up in the brain during sleep
what is the ‘Opponent Process Theory’ of sleep
alertness affected by opposing two biological factors circadian time and homeostatic pressure
circadian time:
- provides an arousal signal
- reaches a peak in late afternoon/early evening opposes the sleep prpensity signal
Homeostatic pressure:
- time spent awake
- increasing time spent awake produces greater drive to sleep
what happens in individuals who do shift work
their biorhythms remain entrained to 24 hour day - results in performance deficits and health stressors
increased time and intensity of 2nd night sleep
what does caffeine do
acts as an adenosine receptor antagonist and makes our brain less susceptible to the drowse-inducing effects of adenosine
what is the “flip-flop” switch theory
what neurotransmitters go on the sleep side and which ones go on the awake side
Sleep:
- VLPO
- GABA
Awake:
- orexin
- brain stem LC and Raphe
- norepinephrine and 5-HT
what are developmental differences seen in infants & children, and in the elderly
Newborns: sleep 17-18 hours a day (sleeping 3-4 hour sessions)
Toddlers: sleep in a diurnal (twice daily) pattern- single daytime nap and nighttime sleep
6 year olds: consolidate into a single sleep period- 10-12 hours nocturnal sleep
adolescents: prone to later “phase dealy” stay up late and sleep late (night owl)
young adult: 6-8 hours
Elderly: have early ‘phase advance’ go to bed early and get up early. Diminished quality and duration of sleep: awaken more easily
what are nightmares vs. night terrors and in what sleep stages do they occur
nightmares occur in stage 5 of sleep (same stage as REM), night terrors occur in sleep stage 4 (during delta wave sleep). You usually remember nightmares (like regular dreams). You may have physical signs of fear and stress during a night terror but you do not remember it when you wake up.
when does sleep walking occur
sleep walking occurs during the 4th stage of sleep (delta waves)
are sleep problems a major issue in the US (what % of individuals have sleep disorders)
35-40% of the adult population experiences sleep problems
what is insomnia and stress insomnia
Insomnia: Trouble going to sleep or staying asleep.
Stress insomnia: Can increase brain aminergic activity (NE, DA, 5-HT) adn shift brain to hyperarousal. stress, disease or genetic predisposition
table 2. pg. 493: DSM-5 criteria for insomnia disorder
A. a predominant complaint of dissatisfaction with sleep quantity or quality associated with one + of the following symptoms:
1. difficulty initiating sleep
2. difficulty maintaining sleep
3. early mornign awakening with inability to return to sleep
B. the sleep disturbance causes clinically insignificant distress or impairment in social, occupational, educational, academic, or other important areas of behavioral functioning
C. difficulty occurs at least 3 nights per week
D. difficulty is present at least 3 months
E. difficulty occurs despite adequate opportunities to sleep
F. not better explained by and does not occur exclusively during the course of another sleep-wake disorder
G. not attributable to physiological effects of a substance
H. coexisting disorders/medical conditions do not adequatley explain the predominant complaint of insomnia
how is insomnia treated
- sleep restriction therapy
- CBT
- medications including: antidepressants, antihistamines, tryptophan, delta-sleep-inducing-peptide (DSIP), melatonin, and benzodiazepines (GABA agonist), orexin receptor blocker
what is narcolepsy and what sleep stage is it linked to
Narcolepsy is triggered by excitement and positive emotions; it is an abrupt drop into REM sleep
what animal was used for research in the discovery of the gene linked to narcolepsy
dogs
what type of receptor does the narcolepsy gene code for
Orexin
the treatment for narcolepsy involves ____ drugs targeted at improving sleep and ____ drugs targeted at staying awake
GABA agonist, stimulants
what is sleep apnea and how is it treated
sleep apnea is cessation of breathing for > 20 seconds or cessation for 10 seconds with low resp. rate and a drop in O2 and heart rate.
Central sleep apnea is normla decline in drive from respiratory brain center during sleep. An exaggeration of this can produce sleep apnea.
Obstructive sleep apnea is mechanical collapse and compression of airway.
Define circadian sleep disorders
abnormalities in length, timing, and/or rigidity of the sleep-wake cycle relative to the day-night cycle.
- delayed sleep phase disorder
- advanced sleep phase disorder
- non-24 sleep-wake disorder
- shift-work disorder
what is advanced sleep phase disorder
- ealy morning awakening and inability to maintain wakefulness into the evening. Typically awake from 4am to 8pm
which is associated with a ‘morning lark’; a ‘night owl’
morning lark: advanced sleep phase syndrome
night owl: delayed sleep phase syndrome
what is ‘non-24’ sleep wake syndrome
individuals fail to entrain to the 24 hour day. It is frequent in blind individuals. May occasionally coincide to real day night, but becuase free-running clock is 24.5 hours they drift out of phase. They tend to have night time insomnia and day time sleepiness. Taking melatonin in 24 hour intervals tends to help
what is the rate of adjustment to local time, or a ‘phase-shifted’ environment’ in those who fly across several time zones
one hour per day
