A new study reveals that insomnia of older adults may be caused by the quality of sleep and other health issues, rather than the amount of sleep that the person gets.

Insomnia, which is defined as the difficulty to fall and stay asleep throughout the night, often increases along with the aging process. Studies show that almost half of older adults have experienced at least one symptom of insomnia.

Experts on the matter think that the lack of good, restorative sleeping could lead to health conditions such as heart diseases, falls and declines in mental processes and daytime functions.

The new research, which comes from the University of Chicago, compared the data compiled by a wrist actigraph, which is a sensor that looks like a wristwatch which tracks a person's sleeping patterns and movements, to the sleep perceptions recorded by the study's subjects within a sleep booklet.

The participants, who numbered a total of 727 older adults, received random invitations to participate in an "Activity and Sleep Study." The study was divided into two parts. The first part was the sleep diary for each participant, which requested them to answer questions regarding their sleep experiences. The second part was the requirement to wear the wrist actigraph for a period of 72 hours.

Linda Waite, one of the authors of the study, said that the team of scientists wanted to evaluate objectively many aspects of the characteristics of the sleep of older adults, which is why there were two components to the study.

"Older adults may complain of waking up too early and not feeling rested despite accumulating substantial hours of sleep," Waite said.

Researchers found significant differences between what the participants reported in their sleep booklets compared to the measurements taken by the wrist actigraphs.

The measurements taken by the actigraph revealed that most of the older adults received what is thought to be sufficient amounts of sleep. Survey results also show that 13 percent of the participants said that they never or almost never feel completely rested once they wake up in the morning.

The survey also showed that 12 percent of the participants have trouble falling asleep and 30 percent indicated regular problems of waking up in the middle of the night.

The actigraphs showed that the average sleep period among participants was 7.9 hours and the average total sleeping time was 7.25 hours, revealing that most older adults are able to get the recommended amount of sleeping time.

Another unexpected result was that the participants that said they were waking up more often in the middle of the night had higher total sleep times.

"This suggests that a question about feeling rested may tap into other aspects of older adults' everyday health or psychological experience," Waite said.

The analysis and findings of the research was published online at the Journals of Gerontology: Medical Sciences.