Mar. 23 --
MONDAY, April 16 (HealthDay News) -- Insomnia's effects may depend on just when a person prefers to hit the sack.
According to new research, "night owls" suffer more from insomnia than those who try and get their z's earlier on.
Night owls also tended to be more concerned about their insomnia than the early-to-bed folks, despite the fact that they actually spent relatively more time in bed and got more sleep overall, the researchers found.
"We suspected that there may be more severe symptoms among night owl insomniacs," said the lead author, Jason C. Ong, an instructor of psychiatry in the Sleep Disorders Clinic at Stanford University in Palo Alto, Calif. "But we also found they exhibited much more distress about their sleep, in terms of attitude. They felt they needed eight hours of sleep, and they're not getting it, and that was associated with feelings of depression and irritability and that kind of thing."
Ong and his colleagues published their findings in the April 15 issue of the Journal of Clinical Sleep Medicine.
According to the researchers, physiological "insomnia" -- which affects 30 percent of American adults -- refers to disorders defined by poor sleep quality and difficulties falling and staying asleep.
By contrast, another type of sleep disturbance, known as a "circadian rhythm sleep disorder" (CRSD), can arise when the hours of your natural internal clock do not line up well with your social or professional schedule. The resulting "mismatch" can undermine your ability to fall asleep or wake up.
Traditionally, CRSD has been viewed as distinct from insomnia. Experts have theorized that when circadian rhythms match your daily schedule, you should theoretically experience problem-free sleep.
The new study focused on 312 outpatients (60 percent women) who had already started to undergo group behavior therapy for insomnia at the Stanford sleep clinic between 1999 and 2004.
Ong and his team asked all the men and women to indicate their usual (pre-insomnia) preference for sleep scheduling -- when they liked going to bed and waking up.
Based on that information, the patients were characterized as either "morning larks" who felt best going to bed early and rising early, or "night owls" who hit the sack late and slept in. There were also "intermediate" types who fell somewhere in between.
After sorting the participants according to their sleep preference -- or "chronotype"- the authors then reviewed week-long sleep diaries that annotated time of lights out, number of awakenings during sleep, time spent out of bed during sleep time, sleep quality, total time spent sleeping, and all sleep-aid drugs consumed.
In addition, a series of psychological surveys were administered to detect depression, frustration and negative beliefs related to either insomnia or sleep in general.
The Stanford team found that night owl insomniacs spent more time out of bed while trying to sleep, and generally experienced more sleeplessness than either morning larks or intermediate type insomniacs.
Night owls also displayed the most erratic bedtime and wake-time habits, and were relatively more depressed and more frustrated by their insomnia. For example, the "owls" expressed more concern than the others about the consequences of insomnia and their inability to control sleep.
They made up for such deficits by choosing to spend more time sleeping. In this way, they actually racked up more total sleep time than the other study participants.
No group differences, however, were found with respect to the number of times patients awoke during sleep, in their use of sleep-aids, or in the quality of their sleep.
The findings applied equally to men and women.
According to Ong's team, your natural sleeping schedule preference appears connected to the nature of your insomnia. They emphasized, however, that the findings only point to an association between sleep-time preferences and insomnia, rather than any cause-and-effect relationship.
They also cautioned that clinical measures of sleep -- such as blood levels of cortisol, melatonin, or changes in body temperature -- were not evaluated. Some of the patients also had medical conditions that could have affected their sleep patterns.
Nevertheless, Ong and his colleagues believe the findings could someday lead to targeted treatments that hone in on the patient's unique "insomnia profile."
"It would be premature to recommend any particular treatment at this point," said Ong. "The goal here was to learn from our patients. So this is more of a starting point that will hopefully stimulate more research into this area and help to develop some guidelines. But now we can say that maybe we should consider the idea of tailoring intervention and treating people differently, in light of this association."
Another sleep expert agreed more research is needed.
"To me this study underscores the urgent need for researchers to take more seriously the kinds of insomnia that people present with," said Michael L. Perlis, director of the University of Rochester's Sleep Research Laboratory.
He noted that while some patients have trouble falling asleep, others have trouble staying asleep or waking up too early, or any combination thereof.
"People don't experience one form of disorder or another for no reason," he said. "Maybe the reason is related to their chronotype, as is suggested by the Ong study. Maybe it's related to how people manage their insomnia? These issues need to be worked out, so that we can better define the disease and in so doing develop better treatments."
There's more on insomnia at the U.S. National Institutes of Health.
SOURCES: Jason C. Ong, Phd, instructor of psychiatry, Sleep Disorders Clinic, Stanford University, Palo Alto, Calif; Michael L. Perlis, Ph.D. associate professor, psychiatry and neurosciences, and director, Sleep Research Laboratory, University of Rochester, N.Y.; April 15, 2007, Journal of Clinical Sleep Medicine.