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ADVANCED SLEEP PHASE SYNDROME
Approximately 20% of those with weak circadian rhythms suffer from Advanced
Sleep Phase Syndrome (ASPS). In this case, their body clocks tend to
speed up when they don’t get a strong enough stimulus of light. Their
body clock will advance to an earlier time of day.
Most people in this category fall asleep easily, and usually earlier
at night. However, they can only stay asleep for a few hours and are
up again. Many can not get back to sleep and finally get out of bed
in the early morning. Others can not get back to sleep for hours and
might get another
Those
with ASPS fall
asleep easily, stay
asleep for a few hours
and experience early
awakening.
hour or two of sleep. In either case, they don’t need an alarm clock
to wake them up, and they usually get out of bed because they just can’t
get any more sleep. ASPS is also more common (but not limited to) in
the elderly population. Apparently, some body clocks may tend to speed
up with age.
Similarities in both DSPS and ASPS
In both DSPS and ASPS, sufferers may
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experience insomnia during the night time. However, the rule of thumb
is if the person falls asleep easily, but only gets a few hours of consistent
sleep, he/she should try the lightbox in the evening.
Treatment Schedule for ASPS
Again, most people are unable to go to a sleep lab to determine their
body temperature drop, but they can get pretty close by examining their
natural sleep/wake cycle. Recall that people usually wake up approximately
one to two hours after their ‘peak time’. For example, if one wakes
up around 4:00am, his/her subjective peak time would be around 2:00am.
If a very strong stimulus of light is received before 2:00 am (exp.
1:00am), it will slow the circadian rhythm down and reset the body clock
as much as two hours later, causing awakening at 6:00am. However, receiving
light this late in the night is impractical and could cause an inability
to sleep for that entire night.
Whereas DSPS requires that light be administered within an hour or two
after the body temperature minimum, this does not appear to be the case
with ASPS. Receiving light as early as 6:00pm can be effective. However,
finding the optimum time to use evening light is more difficult. Doctors
will recommend starting at 6:00pm or 7:00pm for one to two weeks and
then moving an hour later for a few days, and then another hour later
etc. until the desired wake-up time is reached.
Light should not be administered past 9:00pm. Bright light will suppress
the production of melatonin, and it usually takes a couple of hours
before melatonin will again be released. If bright light is used past
9:00, it will be difficult to fall sleep until after 11:00pm.
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Advanced circadian
rhythm (waking time 4:00 a.m.-). Body temperature drop has shifted to
2 a.m. or earlier.
When in Doubt
ASPS affects the minority of SAD sufferers, and the symptoms may not
be as easy to recognize as DSPS. If there is any question whether morning
light or evening light should be used, most doctors will recommend using
morning light for a couple of weeks and then switching to evening light
if no benefit was found from using morning light.
ADAPTING TO SHIFT WORK
Instructions for ASPS are virtually the same for shift work even though
the shift worker may not suffer from either DSPS or ASPS. Receiving
bright light in the evening time while avoiding morning light will shift
the body clock to a night schedule.
The shift worker must first determine when he/she wants to wake up,
and receive bright light at that time. Care must be taken to avoid any
bright light when coming home from work and going to bed. This schedule
should shift the body clock within two weeks.
Shifting the Body Clock Faster
Shifting the body clock can be accelerated by receiving bright
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