What’s affecting your sleep in 2010: Shift work to ‘sexsomnia’

By Caitlin Hagan
CNN Medical Associate Producer

SLEEP 2010 the 24th annual meeting of the American Academy of Sleep Medicine and the Sleep Research Society, is happening now in San Antonio, Texas. The findings ranged from how shift work affects sleep patterns to having sex while you’re asleep. Read on for more details.

Tired? Can't sleep? It might be your job.

How tired you are and how much sleep you get may depend on what time of the day you work. A new study being presented at SLEEP 2010 predicts that day shifts allow workers to get more sleep than night shifts, and a night shift that begins after midnight may be better than a shift that starts at 11 p.m. Specifically, people who started work between 9 a.m. and 2 p.m. slept the longest, while those who started their shift after 8 p.m. but before midnight, slept the least. The number of hours varied from 4.5 to eight hours.

By creating 24 separate six-day work schedules with varying shift start times by one-hour increments , researchers found late-night workers had less sleep and poorer performances at work. When it came to early early shifts, meaning those after midnight, studies found those workers were actually better rested because most of them slept right before their duty periods. In contrast, shifts that started just before midnight did not allow for pre-shift sleep because the timing conflicted with the body's early evening circadian process, better known as the body's inner clock.

"Shifts of equal duration differ in how fatiguing they are depending on the time of day when they are scheduled," said lead author Angela Bowen, research assistant at the Sleep and Performance Research Center at Washington State University Spokane.

"The same limitation on the number of duty hours may be either overly restrictive if during the day or too liberal if during the night."

Because of these statistics, experts at the conference believe labor regulations should also provide guidance to employers on shift start times, so companines may maximize their workers' sleep opportunity and minimize their risk of on-the-job fatigue.

Sex while you sleep?

Sexsomnia, defined by the American Academy of Sleep Medicine as the act of initiating or engaging in sexual activity with a bed partner while asleep, seems to be a common sleep disorder among patients being treated at sleep centers. Researchers conducted a retrospective chart review of more than 800 patients who were evaluated at one sleep center for possible sleep disorders. While answering questionnaires, 8 percent of patients admitted to acts of sexsomnia and male patients were three times more likely to report sexsomniac activity. Yet only four patients of the entire pool actually raised the issue with their doctor or specialist.

Study investigator Sharon A. Chung, Ph.D., Sleep Research Laboratory staff scientist at the University Health Network in Toronto , Canada, said in a press release, "while our finding of eight percent of people reporting sexsomnia seems really a high number, it should be stressed that we only studied patients referred to a sleep clinic. So, we would expect the numbers to be much lower in the general population."

Sexsomnia is classified by the American Academy of Sleep Medicine as a parasomnia, or an undesirable behavior that occurs while a person is falling asleep, sleeping, or waking up. According to the researchers, the study was the first of its kind to measure how frequently sexsomnia occurs.

Too much sleep may be bad for your health

It's a unique headline: For adults over the age of 50, sleeping longer than eight hours a night may actually have negative health implications. Study participants who slept more than eight hours, including naps, had a 15 percent higher chance of developing metabolic syndrome, a group of risk factors that increase a person's risk for heart disease. The study could not determine the cause of this assocation.

"The most surprising aspect of our study was that long sleep – and not short sleep – was related to the presence of the metabolic syndrome," lead author Teresa Arora said in a press release. Arora is a research scientist at the University of Birmingham School of Medicine in Birmingham , U.K.

The study involved more than 29,000 adults. The association remained true even after researchers accounted for lifestyle factors and other metabolic markers.

Regular, early bedtimes linked to smarter preschoolers

Preschool-aged children with established, regular bedtimes scored higher on a range of developmental assessments than children without. Researchers used a nationally representative sample of approximately 8,000 children to determine that children 4 years of age who had regular bedtimes and got ample sleep had higher math, literacy, and expressive language abilities.

"Getting parents to set bedtime routines can be an important way to make a significant impact on children's emergent literacy and language skills," lead author Erika Gaylor, Ph.D., early childhood policy researcher for SRI International, an independent, nonprofit research institute in Menlo Park, California, said in a press release.

"Pediatricians can easily promote regular bedtimes with parents and children, behaviors which in turn lead to healthy sleep."

CNN Producer Val Willingham contributed to this blog.