00:00
How do we diagnose a circadian rhythm sleep-wake disorder?
Well, the diagnosis is made clinically. Polysomnography or a
sleep study is not
required but can be performed particularly to rule out other
explanations. When
we diagnose one of these disorders, a sleep diary is really
helpful. It's useful as a
self-reported tool to aid in the diagnosis and understand
when the patient is going to
bed, when they tend to get to sleep, and when they wake up.
The patient is asked to
record the bedtime, wake up time, total sleep time,
estimated time that is required
to fall asleep, and the frequency of awakenings at night.
And this can help us to put
together that pattern of sleep over a typical night and
week. Actigraphy can also be
helpful. This is a movement sensor worn on a patient's
non-dominant wrist to
determine the total amount of time and the sleep efficiency.
This is useful in cases
where a sleep diary is not feasible such as patients with
neurodegenerative disorder
or stroke or other conditions that may limit the quality of
a sleep diary. Melatonin
sampling can also be performed in particularly difficult or
challenging cases. This
can provide an objective assessment of impaired circadian
rhythm. Melatonin is
the key naturally occurring substance that helps to promote
sleep. It's released by
the pineal gland around 90-100 minutes before usual bedtime.
And it is suppressed
by bright lights when we wake up and the light stimulus hits
our eyes, this
suppresses further melatonin secretion. Dim light melatonin
onset protocol can be
used to measure melatonin secretion and evaluate for
deficiency in melatonin
secretion that could contribute to a change in the circadian
rhythm. How do we
manage patients with circadian rhythm disorders? Well, it
depends on the disorder.
01:57
For delayed sleep-wake phase disorder, we talk about sleep
hygiene, minimized
light exposure during the evening to help bring that sleep
onset time earlier in the
evening. Light therapy during early morning can help promote
a consistent
wakefulness and also reset the circadian rhythm to earlier
in the night. Melatonin
can be administered early in the evening to promote earlier
sleep and advancing
bedtime each night can also be helpful where the patient
starts at his or her normal
hour of sleep and then moves it 1 hour earlier each night to
the desired onset of
sleep. Advanced sleep phase disorder. Management strategies
here include light
therapy in the afternoon or prior to bedtime, again to help
modulate and reset the
circadian rhythm. Irregular sleep-wake rhythm disorder. We
think about light
therapy in the morning to generate a consistent onset of
wakening as well as
behavioral interventions to consolidate sleep and increase
daytime social and
physical activities. For non-24-hour sleep-wake rhythm
disorder, light therapy to
have a consistent on of the brain, melatonin delivered at
night to reset that
circadian rhythm to a 24-hour period can also be helpful and
then some melatonin
agonist can be considered in selected patients. For shift
worker sleep disorder, we
think about light therapy as well as modafinil which can be
a helpful wakefulness
promoting agent taken at the time that the patient needs to
wake up and go to work.
03:39
And then for jet lag disorder, this is often self-limited
and doesn't need therapy,
but melatonin can be helpful in some patients.