Circadian Sleep Disorders Flashcards
To cause a phase advance, should bright light be used before or after a temperature nadir (bottom)?
After
Bright light after temperature nadir = phase advance (earlier in day)
Bright light before temperature nadir = phase delay (later in day)
What is the normal DLMO?
In DSPD?
In ASPD?
8 to 10 pm is normal
In DSPD it is delayed by hours
In ASPD it is advanced by hours
In patients with DSPD do they have a normal ability to compensate for sleep loss?
No. They are not able to compensate as well.
What circadian sleep disorder has a strong genetic basis?
ASPD (PER2 gene)
In ASPD when should melatonin be taken?
When should light therapy be used?
- Melatonin: Early in the AM (it should be several hours after the temperature nadir). Melatonin pulls the rhythm towards it (thus causing a phase delay).
- Light: Late evening (7 to 9 pm). Light pushes the rhythm away from it (thus causing a phase delay).
What has a stronger effect on circadian rhythms, light or melatonin?
Light
What is non-24-hour sleep-wake disorder and in what group of people is it most commonly seen?
It is a free running disorder is which there is a daily phase delay (shifing to the right).
It is most commonly seen in blind people
Circadian disorders are common in what 3 medical conditions?
- Hepatic encephalopathy
- Parkinson’s disease
- Dementia
When does DLMO typically occur?
2 to 3 hours before habitual bedtime
Core Body Temperature minimum (CBTm) typcially occurs when?
2 to 3 hours before sleep offset (normal wake time)
How can CBTmin be calculated using DLMO?
DLMO + 7 hours
What is the best treatment for non-24 hour sleep-wake disorder?
Melatonin 1 hour before desired bedtime
What is the best treatment for DSPD?
What is the next best treatment?
Bright light for 30 minutes shortly after CBT min
Melatonin given a few hours prior to desired bedtime
How long does it take for the human biological oscillator (known as Tau) to complete one cycle?
24.2 hours
How many time zones must be crossed to meet a diagnosis of Jet lag disorder?
2 or more time zones
Which requires a phase delay, flying east to west or west to east?
Flying east to west. It requires you to stay awake longer (thus delaying sleep at the new normal time)
Which requires a phase advance, flying west to east or east to west?
Flying west to east (since you will be have to be awake earlier to be on the same schedule as those on the east coast - you advanced)
Which is easier to adapt to, west to east travel or east to west and why? After how many times zones travelled is the least beneficial?
- East to West. It’s a phase delay. Since our circadian clock is a natural phase delay (24.2 hours) we are naturally able to stay up later than go to bed earlier.
- 8 time zones
What happens when a patient with a predisposition to DSPD is exposed to bright light in the evening?
It causes a phase delay as they are hypersensitive to melatonin suppression with bright light exposure
How long is the circadian rhythm in ASPD?
Less than 24 hours
What is chronotherapy?
What circadian disorder is it used in?
Progressively delaying sleep and wake times by 3 hours every few days until they reach the desired sleep time.
It is used in DSPD
Treatment for Non-24-hour sleep-wake disorder (4 things)
- Bright light in AM
- B12
- Rapid release melatonin or tasimelteon (Hetlioz) 20 mg
- Sleep hygeine
What medical condition is delayed sleep phase syndrome seen in 33% of patients?
Chronic liver cirrhosis
