August 28 (HealthDay News) -- Older adults who live with and provide direct care during the night for someone with dementia have significantly worse sleep than other older adults, U.S. researchers say.

The study compared 31 caregivers and 102 noncaregivers, ages 60 to 89. Caregivers slept about 33 minutes less per night than non-caregivers and took about 10 minutes longer to fall asleep. Caregivers also had more variable sleep from night-to-night, reported lower sleep quality, more daytime sleepiness, and more symptoms of depression.

"On average, caregivers, only slept about six-and-a-half hours a night and took almost 23 minutes to fall asleep," primary investigator Meredith Rowe, an associate professor at the University of Florida, said in an American Academy of Sleep Medicine news release.

"Using the sleep diary data that subjects kept at the same time, however, depression was the primary determinant of poor sleep, with depressed subjects reporting less time asleep and more wake time over the week," she said.

Rowe and colleagues were surprised by the finding that caregivers took a longer time to fall asleep, which is consistent with the increased worry and concern that may burden them.

The researchers said they expected the caregivers' main cause of sleep loss to be more time awake during the night when the person with dementia required supervision. However, both caregivers and non-caregivers had an average of more than 40 minutes of time awake during the night after initially falling asleep.

The study was published in the Aug. 15 issue of the Journal of Clinical Sleep Medicine.

SOURCE: American Academy of Sleep Medicine, news release, Aug. 15, 2008