Oct. 15, 2007 -- Getting enough sleep? Probably not.
A new study in the Journal of Clinical Sleep Medicine finds that people tend to overestimate — not underestimate — the amount of sleep that they get.
The finding could add weight to the idea that Americans already skimp too much on sleep. And since many of us may be sleeping even less than we think, our lack of shut-eye may go largely unnoticed.
"People are losing sleep," says lead author Graciela Silva, assistant professor, college of nursing and health care innovation, at Arizona State University. "Although seven and a half to eight hours are recommended, people sleep, on average, six hours each night," she said.
But the surprise lay in the fact that most of the time, people were unaware that they were getting so little sleep.
"What is innovative and unexpected is that the older adults overestimated their sleep, rather than underestimated it," said Dr. Phyllis Zee, director of the sleep disorders center at Northwestern University in Chicago, Ill.
"As for the issue of sleep in our society, it looks like we are sleeping even less than we thought — which is often insufficient for mental and physical health to begin with," said James Olcese, associate professor of the department of biomedical sciences at Florida State University College of Medicine in Tallahassee, Fla.
The findings of the study are further driven home by its sheer magnitude. A total of 2,113 participants, aged 40 years or older, participated in the study. Rather than taking a sample from a patient population known to have sleep problems or illnesses, this study examined a population largely representative of the general population.
And participants did not even have to leave their own bed. Unlike previous studies that required participants to be present in the sleep lab to undergo tests, in this study, researchers, instead, followed subjects into their own homes.
There, the technicians hooked participants up to a polysonogram, a sleep test that measures brain waves to determine the amount of sleep they are actually getting.
The Morning After
The next morning, participants were asked to report how much sleep they felt they routinely enjoyed, as well as how many hours of sleep they believed they had the previous night.
What researchers found was that participants consistently overestimated the amount of sleep they actually got. They estimated that they typically slept seven hours, but the polysonogram recorded a modest six.
Olcese said the results suggest that researchers may be better off conducting objective tests like polysonograms, rather than patient questionnaires, when it comes to figuring out exactly how much sleep a person is getting.
"Simply put, this study reminds us that what people say that they are doing is not always exactly correct," he said. "Personal subjectivity usually biases the results of questionnaires somewhat, so don't believe everything you hear, unless there is objective confirmation.
"These findings draw attention to the need for objective measures of sleep parameters, rather than using subjective evaluations."
However, the findings were not shocking to everyone.
"This really does not surprise me," said Dr. Nancy Collop, medical director of the Johns Hopkins Hospital Sleep Disorders Center, in Baltimore. In her sleep studies, she has found that patients routinely misperceive how much they sleep, often stating "I didn't sleep at all."
Less Sleep — What's the Difference?
Not getting enough sleep may be so pervasive within our society that many may not view it as a big problem.
However, missing out on sleep is more detrimental than many may realize.
"As we have progressed, people are losing sleep time," explained Silva, who is concerned that a sleep deficiency may affect daily functioning. This, she said, underscores the implications of her research for the thousands of physicians who routinely ask patients about their sleep habits.
"Physicians should take into account that people overestimate their sleep time," Silva said.
Zee agrees, and added that doctors often rely on subjective reports. "So, doctors need to be cognizant that older adults may be overestimating, and if they are actually getting less sleep, [it] may be associated with increased risk for cardiovascular, metabolic conditions that have been associated with short sleep duration."
More ZZZZs, Anyone?
Fortunately, there are steps that those wishing to maximize their sleep, or improve its quality, may take. These include refraining from heavy meals, hot baths, or vigorous exercise close to bedtime.
Caffeine lovers should avoid caffeinated beverages late in the day, and technology connoisseurs should relocate all of their noise-making gadgets — including computers and televisions — out of the bedroom.
If all else fails, and you are not rested after sleeping, Collop suggests actively trying to get more sleep.