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Andy
Coghlan
New
Scientist September 16,2000
People who are
totally blind don't sleep too well at night. Their body clocks
go awry because they can't sense any light, so they can't
tell night from day. Now researchers have found a treatment:
the anti-jet-lag hormone, melatonin.
"Light
is the major time cue in humans," says Debra
Skene of the University of Surrey in Guildford. In sighted
people with normal body clocks, levels of melatonin in the
blood peak at around 4 am. In totally blind people, melatonin
peaks at a different time each day. Their sleep suffers, so
they often nap during the day to compensate for their disturbed
nights.
Skene wondered
if the body clock of completely blind people could be reset
with daily doses of melatonin. In an experiment on seven totally
blind volunteers with severe sleep disruption, she found that
the melatonin treatment gave most a better night's sleep,
with fewer daytime naps.
Later she found
that the treatment only reset the clock if it was timed correctly
in relation to the subject's own melatonin peak. "Melatonin
can work, but we need to know the status of the clock before
we begin treatment," she says.
New
Scientist,
September 16, 2000
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