“We expected these results before the survey because some studies
already suggested that acute change of sleep-wake pattern is likely
to cause daytime sleepiness and/or psychological distress,” said
lead author Shoichi Asaoka of Edogawa University in Nagareyama.
In this study, the change in mental quality of life was larger than
for physical quality of life, Asaoka told Reuters Health by email.
Past studies have found that shifting sleep patterns can affect
performance and mental health for adults and teens. And college
students typically stay up later and later every year they are at
school, the researchers note.
To see what happens when those students graduate and abruptly have
to adjust to the schedule of the workaday world, the team of
Japanese researchers used online questionnaire data from 745
university students, an average of 22 years old, and 360 recent
graduates with an average age of 24 who were working full time.
The questions addressed employment status, current sleep habits and
perceived sleep quality, symptoms of depressed mood and aspects of
quality of life. The participants were also asked to recall their
sleep habits from one year earlier.
Students tended to go to bed later and wake up later with each
successive year of college, but switched to an “advanced sleep
phase” with earlier wake up times after graduation. Graduates also
tended to spend about an hour less in bed than students.
New graduates who reported going to bed earlier than they had one
year earlier were more likely to be experiencing symptoms of
depressed mood and poor sleep quality than others who had gone to
bed earlier the previous year as well as the current year.
Those problems did not seem to be connected to wake-up time or total
time in bed, according to the results published in Sleep Medicine.
“When you just see an association between factors at one point in
time you don’t know if there’s a causal direction,” said Yvonne
Kelly of the Research Department of Epidemiology and Public Health
at University College London, who was not involved in the study.
“It suggests, as does lots of other work in this area, that change
in sleep pattern can have an effect on general quality of life, and
it raises lots of other questions,” Kelly told Reuters Health.
“An explosion of these studies in the last few years” have
investigated different aspects of sleep, "including regularity and
pattern, which seem to be hugely important," Kelly said.
It’s similar to traveling across time zones, when your internal
clock and the external clock around you don’t line up, and you can
be “messed up” for a few days at least, she said. But in the context
of university and “adult” life, we don’t know how long that rocky
transition period might persist.
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“There’s definitely something to sleep timing,” said Stephanie J.
Crowley, who studies sleep at the Biological Rhythms Research
Laboratory at Rush University Medical Center in Chicago, was not
part of the new study.
Experts have found that for working adults, even having a delayed
sleep pattern on the weekends compared to weekdays can lead to
“social jet lag,” which has been associated with an increased risk
of obesity, Crowley said. The current study only included data for
weekday sleep, she noted.
“Probably the best advice to give young adult workers is to try to
keep your sleep schedule as consistent as possible,” Crowley said.
This study does target an important life transition, she said, but
there could be many other stressors and social or cultural factors
“There are some dos and don’ts of what people recommend individuals
do to improve sleep, like brushing your teeth before bed, not having
caffeinated drinks, and no screen time in the hour or so before
bed,” Kelly said. “I think having a regular schedule makes a lot of
The study authors suggest that preventing a major change in sleep
phase, perhaps by sticking to a more work-like schedule while at
university, could make adjusting to a job easier.
“That makes sense but I don’t know how that actually works out in
real life,” Kelly said. “If you don’t have constraints and you want
to go out and see your friends at school, you will.”
Sleep Medicine, online June 13, 2014.
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