SLAVISH adherents to the eight-hours-a-night sleep rule can
relax. Research suggests we all have our own sleep patterns that
change according to how much shut-eye we get. For the first time
a team from the University of Sydney has tracked people's
nightly patterns and found sleep naturally increases and
decreases throughout a week. "The body seems to have a way of
adjusting the amount of sleep we require," said the study
leader, Chin Moi Chow. ''If you incur a sleep debt, your body
will signal a need to catch up on extra sleep.'' Her study found
each person had a different sleep cycle, with some taking only a
couple of days to catch up, and others taking up to 18 days.
Unlike some previous research, she did not find the participants
made up for lost sleep on the weekend. Rather, the 13 young men,
whose sleep was measured over a two-week period using a device
worn on their arms, made up the sleep at different times,
getting up to two hours more sleep on some nights than others.
This suggested the timing of ind