By Kathryn Doyle
NEW YORK (Reuters Health) - For recent college grads who are used to staying up late and sleeping in, switching to a regular job schedule might make it harder to function during the day, according to a small new study from Japan.
“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.
“There’s definitely something to sleep timing,” said Stephanie J. Crowley.
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 at play.
“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 sense.”
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.”
SOURCE: http://bit.ly/VzOwWl Sleep Medicine, online June 13, 2014.