FERNWOOD FITNESS - PULSE eMagazine - Issue#10 - Flipbook - Page 58
rhythms cycle about once
every 24 hours, without
light and dark (for instance
with total blindness) humans
actually 琀椀ck a li琀琀le more
slowly – about 24.1 hours.
Thus, if we didn’t have
daylight we would get out of
synchrony with night and day.
People with Delayed SleepWake Phase Disorder
(DSWPD) have trouble
adjus琀椀ng and go to bed and
wake up late, which can be
inconvenient when trying
to schedule ac琀椀vi琀椀es such
as work and school. Shi昀琀
workers o昀琀en have trouble
totally adjus琀椀ng to being up at
night and sleeping in the day.
The external light/dark cycle
and tends to keep them
on a day shi昀琀 pa琀琀ern. The
in昀氀uence of light also explains
why we can adjust to a new
琀椀me zone if we 昀氀y abroad.
The light in the new 琀椀me
zone sends a signal to our
clock which causes it to get
synchronised with the new
琀椀me zone. This usually takes
several days. Of course, while
we adjust, we su昀昀er from
symptoms of Jet Lag, which
aren’t much fun.
WHY IS THE CLOCK IMPORTANT
FOR SLEEP?
The cycle of sleep and wake is one of the
most obvious circadian rhythms in humans.
Sleepiness is highest at night and lowest in
the day. At night, we get the best quality
sleep, and the longest blocks of sleep
without waking up. Sleep during the day
is more broken up. It tends to be lighter as
well. This means we sleep less. Melatonin
and body temperature are also driven by
the body clock. These are also well-known
circadian rhythms. At night, core body
temperature is low and levels of melatonin
are high. Keeping these rhythms in synch
with each other as well as the external
environment gives us the best chance for
good quality sleep.
