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24 Hours Not Enough? See The Light
Pulses of Bright Light May Reset Body Clock and
Stretch the Day to 25 Hours
By Miranda Hitti
WebMD Medical News
May
2007 -- Get ready for the 25-hour day. A new study,
funded by NASA, shows that it's possible to cram an
extra hour into the day.
The
researchers included Charles Czeisler, MD, PhD,
director of the sleep medicine division at Harvard
Medical School and chief of the sleep medicine
division at Boston's Brigham and Women's Hospital.
They
studied 12 healthy young adults (average age: 28)
who volunteered to spend 65 days living in
individual rooms without windows, clocks, or any
other time cues.
Before the experiment began, the volunteers got
eight hours of nightly sleep at home for at least
three weeks.
When
they reported to the lab, they spent three days on a
normal 24-hour day. Then the researchers tweaked the
hours of light and darkness to pinpoint the
participants' natural circadian rhythm, commonly
called the "body clock."
Next, the scientists tacked on an extra hour of
light to each participants' natural amount of daily
wakefulness.
The
researchers didn't just leave the lights on for an
extra hour. At the end of each "day," the scientists
cranked up the light in the overhead fluorescent
lights, delivering two pulses of extremely bright
light.
The
bright light pulses were nearly 10 times brighter
than normal room light, according to the study.
After the pulses of bright light, participants
didn't go to sleep right away. They stayed up an
extra hour, effectively getting 25 hours per day.
Participants stayed on the 25-hour-day cycle for a
month. They adjusted to the schedule, judging by
their core body temperature and levels of melatonin,
a hormone involved in circadian rhythms.
Before leaving the lab, participants spent three
days on a normal 24-hour schedule.
The
findings may come in handy if astronauts go to Mars.
A Martian day lasts for 24.65 earthly hours, note
the researchers. They argue that without resetting
the body clock to a 25-hour day, astronauts on Mars
would be constantly jetlagged, which could be
dangerous.
Of
course, Mars-bound astronauts aren't the only people
with circadian rhythm issues. Shift workers and
people with sleep disorders may also have body clock
problems.
The
researchers write that "the implications of these
findings are important, because they could be used
to treat circadian misalignment associated with
space flight, shift work, and circadian rhythm sleep
disorders."
The
study appears online in the early edition of
Proceedings of the National Academy of Sciences.
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