is the most common sleep complaint at any age. It
affects almost half of adults 60 and older, according
to the National Institutes of Health.
Old people are known to be lousy sleepers, but a
new study suggests it might all be in their heads,
at least for many of them.
Medications, poor health, bad bedtime habits (such
as watching a movie or drinking
coffee or booze), circadian rhythms, and too much
or too little in their personal "sleep bank"
have all taken the blame for seniors' common complaints
Elizabeth Klerman of Brigham and Women's Hospital
and the Harvard Medical School set out to clear it
up once and for all with a controlled study of 18
subjects ages 60 to 76 and 35 younger subjects, ages
18 to 32, all healthy and not on medication that might
affect sleep. Even people who had crossed more than
one time zone in the past 3 months were disqualified,
as well as those who had worked night or rotating
shifts in the past three years.
After monitoring their sleep
at home, the subjects were regularly instructed to
lie quietly with their eyes closed and to try to sleep,
for as much as 16 hours daily for several days in
a row. They had all the time in the world.
The bottom line was that the seniors simply needed
less sleep — about 1.5 hours less.
Circadian rhythms and preferences
The results are detailed online in the July 24 issue
of the journal Current Biology. Younger subjects slept
for an average of 9 hours compared to 7.5 for older
people, said Klerman and her colleague Derk-Jan Dijk
of the Surrey Sleep Research Centre in England.
The age-related decline in sleep included an even
split between rapid eye movement (REM) sleep, associated
with dreaming, and non-REM sleep, Klerman said.
Klerman and Dijk kept subjects in conditions that
controlled for circadian rhythms by allowing the chance
to sleep during both the night and the day and by
controlling individual choices in sleep opportunities.
While humans sometimes cannot sleep when tired,
there is no evidence that they can sleep when they
are not tired, Klerman explained.
Insomnia and expectations
The results have implications for seniors who think
they have insomnia.
"There are definitely older people with insomnia,"
Klerman told LiveScience. "However there may
also be some older people who 'create' insomnia
if they believe that they 'need' 8 to 9 hours
of sleep and therefore spend more time in bed (lying
awake) than needed to achieve the amount of sleep
"It's also possible that they sleep less
even when given the opportunity for more sleep because
of age-related changes in the ability to fall asleep
and remain asleep," she added, noting that the
new results apply only to healthy individuals taking
no medication and having no medical conditions or
The study also found that most healthy people, and
young people in particular, don't get as much
sleep as they need.
Given the evidence that insufficient
sleep is associated with increased risk of accidents,
errors, decreased learning and immune function, and
metabolic changes similar to diabetes, Klerman encouraged
younger people to sleep more than they currently do.
Ages of sleep
The idea that our sleep habits change markedly across
the life span isn't new.
The same study found another age effect: Given the
same amount of time in bed, older people take longer
to fall asleep.
The researchers set 60 years old as the starting
point for their older subjects to ensure a clear distinction
from the younger group, but it is possible that the
declining capacity to sleep could reach back into
the middle-age years too, Klerman said.
"My expectation is that the change is gradual
and there is no time point at which we 'age,'"
she said. "Sleep changes from infancy, through
childhood, puberty, young adulthood and middle-age
until we die."
The findings may also influence treatment for insomnia
in older people and provoke novel approaches, such
as exercise, new pharmaceuticals or ocular light therapy,
"If older people believe that they need more
sleep than they can achieve even when they spend extra
time in bed, then they may complain of insomnia: being
awake when wanting to be asleep. They may start using
medications needlessly," Klerman said.
However, if seniors are tired during the day, they
should consider an evaluation for a sleep disorder
that may be interfering with their ability to obtain
good sleep at night.
The research was funded by the National Institutes
of Health. Dijk is supported by the Biotechnology
and Biological Sciences Research Council of the United
Kingdom and Wellcome Trust.