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…
