Circadian Mechanisms

Question 1

What is the primary neurotransmitter released by pacemaker cells that controls the circadian rhythm?

Answer 1

GABA

Question 2

What protein do ganglion cells of the eye contain and what function does it play in circadian rhythm?

Answer 2

Melanopsin. It functions as a photoreceptor and helps to synchronize the circadian rhythm

Question 3

How long is the temperature oscillation in Non-24-hour sleep-wake rhythm disorder?

Answer 3

24-25 hours (closer to 24)

Question 4

Timing of circadian rhythms

Answer 4

24 hours

Question 5

Timing of ultradian rhythms

Answer 5

80 to 110 minute REM-NREM cycle

Question 6

Timing of infradian rhythms

Answer 6

Greater than 24 hour cycles

Question 7

2 receptors in the SCN and their function

Answer 7

MT1: Stimulation decreases the alerting signal from the SCN

MT2: Stimulation synchronizes the circadian system

Question 8

Dim Light Melatonin Onset (DLMO) is at what time in normal subjects?

Answer 8

8 pm to 10 pm

Question 9

When does DLMO occur in ASPD vs DSPD?

Answer 9

ASPD = several hours earlier

DSPD = serval hours later

Question 10

Are growth homone and prolactin more influenced by sleep or by circadian rhythm

Answer 10

Sleep with weak circadian influence

Poor sleep will result in decreased GH and prolactin

Question 11

Is TSH influenced more by sleep or circadian rhythms?

Answer 11

Circadian. It will have nocturnal increase even with no sleep. No sleep will actually result in increased levels.

Question 12

In what stage of sleep is lower esophageal spincter tone reduced?

Answer 12

N2

Question 13

Does gastric acid secretion have circadian variability? When are the peaks?

Answer 13

Yes

Between 10 pm and 2 am

Question 14

What pituitary hormone is primarily linked to circadian rhythm?

Answer 14

Adrenocorticotropic hormone (ACTH)

Question 15

What pituitary hormones are primarily linked to sleep?

Answer 15

GH and Prolactin

Question 16

What pituitary hormone is somewhat inhibited by sleep?

Answer 16

TSH

Question 17

Where does thermoregulation take place in the brain?

Answer 17

Preoptic anterior hypothalamus

Question 18

Hot flashes in menopausal women does not occur in what sleep state?

Answer 18

REM

Question 19

Relative autonomic stability in heart rate, rhythm and blood pressure occurs in what sleep stage?

Answer 19

NREM

Question 20

Relative autonomic instability in heart rate, rhythm and blood pressure occurs in what sleep stage?

Answer 20

REM

Question 21

What cardiovascular changes occur in phasic REM?

Answer 21

Increase in sympathetic tone and HR

Decreases in coronary flow in patients with CAD

Question 22

What cardiovascular changes occur in tonic REM?

Answer 22

Increased parasympathetic tone (can decrease HR or cause sinus arrest)

Question 23

What can tonic REM do to patients with long QT3 syndrome?

Answer 23

Torsades de pointes

Question 24

What happens to cerebral blood flow in NREM and REM sleep?

Answer 24

NREM: decreases

REM: increases (to match increased metabolic rate of brain in this stage)

Question 25

When traveling from the West coast to the East coast what are the best sleep adaptations?

Answer 25

Light in the morning and progressively earlier wake time 3 days before. Melatonin 2 to 4 hours before bedtime could also help.

Question 26

What is the rule for time to adapt to new time zones when traveling?

Answer 26

1 day to adapt for each time zone crossed

Question 27

What is the general rule for phase shift advancing vs delaying when traveling East vs West?

Answer 27

• 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