U.S. adults underestimate time slept

Published on Tue 16 Oct 2007

U.S. adults overestimate how much they sleep when compared to measures by a sleep test, a study found.

The study, published in the Journal of Clinical Sleep Medicine, found self-reports of total sleep times tend to be higher than objectively measured sleep times and that the obese and higher educated people reported less sleep time than their counterparts.

Graciela E. Silva of Arizona State University analyzed 2,113 subjects who were 40 years of age or older - 53 percent were female, 75 percent were Caucasian and 38 percent were obese. Silva compared the subjects' total sleep time obtained from unattended home polysomnograms, or sleep tests, to sleep times obtained from the Sleep Heart Health Study Sleep Habits Questionnaire.

Silva found people reported they slept for about seven hours a night but the polysomnograms showed they had slept about six hours, however, both the study participants and the machines said it took about 17 minutes for the subjects to fall asleep.

"The findings from this study suggest that results from studies subjectively assessing sleep times may not be comparable to those using objective determinations," Silva said in a statement.