Circadian Mechanisms Flashcards
What is the primary neurotransmitter released by pacemaker cells that controls the circadian rhythm?
GABA
What protein do ganglion cells of the eye contain and what function does it play in circadian rhythm?
Melanopsin. It functions as a photoreceptor and helps to synchronize the circadian rhythm
How long is the temperature oscillation in Non-24-hour sleep-wake rhythm disorder?
24-25 hours (closer to 24)
Timing of circadian rhythms
24 hours
Timing of ultradian rhythms
80 to 110 minute REM-NREM cycle
Timing of infradian rhythms
Greater than 24 hour cycles
2 receptors in the SCN and their function
MT1: Stimulation decreases the alerting signal from the SCN
MT2: Stimulation synchronizes the circadian system
Dim Light Melatonin Onset (DLMO) is at what time in normal subjects?
8 pm to 10 pm
When does DLMO occur in ASPD vs DSPD?
ASPD = several hours earlier
DSPD = serval hours later
Are growth homone and prolactin more influenced by sleep or by circadian rhythm
Sleep with weak circadian influence
Poor sleep will result in decreased GH and prolactin
Is TSH influenced more by sleep or circadian rhythms?
Circadian. It will have nocturnal increase even with no sleep. No sleep will actually result in increased levels.
In what stage of sleep is lower esophageal spincter tone reduced?
N2
Does gastric acid secretion have circadian variability? When are the peaks?
Yes
Between 10 pm and 2 am
What pituitary hormone is primarily linked to circadian rhythm?
Adrenocorticotropic hormone (ACTH)
What pituitary hormones are primarily linked to sleep?
GH and Prolactin
What pituitary hormone is somewhat inhibited by sleep?
TSH
Where does thermoregulation take place in the brain?
Preoptic anterior hypothalamus
Hot flashes in menopausal women does not occur in what sleep state?
REM
Relative autonomic stability in heart rate, rhythm and blood pressure occurs in what sleep stage?
NREM
Relative autonomic instability in heart rate, rhythm and blood pressure occurs in what sleep stage?
REM
What cardiovascular changes occur in phasic REM?
Increase in sympathetic tone and HR
Decreases in coronary flow in patients with CAD
What cardiovascular changes occur in tonic REM?
Increased parasympathetic tone (can decrease HR or cause sinus arrest)
What can tonic REM do to patients with long QT3 syndrome?
Torsades de pointes
What happens to cerebral blood flow in NREM and REM sleep?
NREM: decreases
REM: increases (to match increased metabolic rate of brain in this stage)
When traveling from the West coast to the East coast what are the best sleep adaptations?
Light in the morning and progressively earlier wake time 3 days before. Melatonin 2 to 4 hours before bedtime could also help.
What is the rule for time to adapt to new time zones when traveling?
1 day to adapt for each time zone crossed
What is the general rule for phase shift advancing vs delaying when traveling East vs West?
- Traveling East
- Phase advance (think East = Earlier)
- Go to bed earlier than you want to
- Traveling West
- Phase delay
- Stay up later than you want to
