An article published in the September 8 issue of Archives of Internal Medicine finds that older women (age 70 and up) are at an increased risk of experiencing falls if they sleep five hours or less per night compared to older women who sleep more than seven to eight hours per night. Author Katie L. Stone, Ph.D. (California Pacific Medical Center Research Institute, San Francisco) and colleagues also found no association between the use of sleep medications and the risk of falling.

The researchers note that, “Falls pose a major health risk among older adults and are a leading cause of mortality [death], morbidity [illness] and premature nursing home placement.” It is known that some 33% of adults age 65 and older experience falls every year, and this population also suffers from insomnia and disturbed sleep. Further, older adults are increasingly using sleep aids such as benzodiazepines (hypnotic medications) to treat insomnia. “It is not established whether it is poor sleep or medications used to treat sleep disturbances that explain the increased risk of falls in those who are prescribed such medications,” add the authors.

Stone and colleagues analyzed a sample of 2,978 women age 70 and older. Each woman wore a wrist actigraphy (like a watch) and kept a sleep diary in order to measure sleep, sleep efficiency (what percentage of time in bed is spend sleeping), and the frequency of falls. Demographic information and data on the use of benzodiazepines were obtained by questionnaires.

The measurements revealed an average of 6.8 hours of sleep per night and an average of 77.2 minutes awake after initial sleep onset. Participants averaged about 0.84 falls in one year of data collection. “A total of 549 women (18.4 percent) had two or more falls during the year after the sleep assessments,” found the researchers.

An analysis of fall risk revealed that women who slept five hours or less per night were at a higher risk of having two or more falls during the following year compared with women who slept more than seven to eight hours per night. A sleep efficiency smaller than 70% was associated with a 1.36 times increase in likelihood of falling compared to a sleep efficiency of 70% or higher. A similar result was seen in women with 120 minutes or more of awake time after sleep onset compared to women with less than 120 minutes of awake time after sleep onset; the former was 1.33 times more likely to fall than the latter.

The research write that, “In all, 214 subjects (7.2 percent) reported current use of benzodiazepines. Use of any benzodiazepine (short and long combined) was associated with a 1.34-fold increase in risk of falls, whereas short- and long-acting benzodiazepine use was associated with an increased odds of 1.43 and 1.18, respectively.”

“Future studies, in particular randomized trials, are needed to determine the effects of newer pharmaceutical interventions for insomnia (e.g., benzodiazepine receptor agonists) or cognitive behavioral therapy for insomnia on risk of falls,” they conclude. “In addition, future studies using comprehensive and objective measures of sleep should examine the interrelationships between specific sleep characteristics (e.g., sleep-related breathing disorder, hypoxia and measures of sleep duration and fragmentation) to determine if these disorders contribute independently toward risk of falls.”

Actigraphy-Measured Sleep Characteristics and Risk of Falls in Older Women
Katie L. Stone; Sonia Ancoli-Israel; Terri Blackwell; Kristine E. Ensrud; Jane A. Cauley; Susan Redline; Teresa A. Hillier; Jennifer Schneider; David Claman; Steven R. Cummings
Arch Intern Med. (2008). 168(16):1768-1775.
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Written by: Peter M Crosta