THE THREE FACES OF INSOMNIA IN OLDER PEOPLE: SLEEP DISRUPTION, DISTRESS AND DAYTIME FATIGUE

Eva Libman, Laura Creti, Nettie Weinstein, Vicki Tagalakis, Rhonda Amsel, William Brender, Catherine S. Fichten

SMBD-Jewish General Hospital, McGill University, Concordia University, Dawson College, Montreal, Quebec, Canada

Psychophysiological factors associated with aging resemble the pattern in non-elderly insomniacs and it seems clear that the changes accompanying normal aging are likely to predispose older individuals to perceive themselves as suffering from a sleep disorder. Despite developmental psychophysiological changes in sleep patterns, not all older adults complain of impaired sleep. To understand this phenomenon we set out to identify those factors which differentiate older individuals who do and those who do not complain of insomnia.

Only relatively recently has the concept of distress related to the sleep problem been recognized as a central feature of insomnia. In evaluating predisposing factors for insomnia, cognitive, affective and lifestyle aspects have usually not been considered. Taking a broadened evaluative approach in our own work resulted in the identification of three distinct categories: good sleepers with no complaints, poor sleepers who were highly distressed by their insomnia and, in addition, another reasonably large group of people who manifested fairly severe sleep disorder, but were minimally or not at all distressed by this. This demonstrates that sleep disruption and distress over poor sleep quality are separable aspects of the sleep experience.

The daytime deterioration of psychosocial functioning often seen among insomnia patients has been proposed as an intervention target in its own right. A recent review of the literature concluded that the relatively small amount of sleep deprivation in many insomniacs cannot account for the magnitude of their complaints or their reported daytime sleepiness and fatigue. This suggests that impaired daytime functioning is yet a third distinct identifiable dimension of the insomnia complaint.

The goals of the present study were (1) to verify that sleep disruption, distress about poor sleep, and perceived impairment of daytime functioning do constitute separate dimensions of the insomnia experience and (2) to evaluate the factors which contribute to each of the three dimensions of the insomnia complaint.

Method

Sample: 189 older individuals were recruited from the community through media publicity (mean age = 70; sex ratio approximately 1/3 male, 2/3 female). According to our experimental criteria, 116 were assigned to one of three sleep status categories: Good Sleepers (n=60), Low Distress Poor Sleepers (n = 29) or High Distress Poor Sleepers (n = 27).

Procedure: Participants completed questionnaires assessing socioeconomic, psychological and physical health factors, as well as sleep parameters and a range of sleep-related behaviors, cognitions and affect.

Results

Analysis of variance comparisons indicated that High Distress Poor Sleepers reported greater daytime sleepiness and more frequent daytime fatigue than did Good Sleepers. Low Distress Poor Sleepers' scores on these variables were similar to those of Good Sleepers.

Correlations between psychological adjustment and sleep variables indicate that adjustment factors were consistently and significantly related to sleep variables with appreciable cognitive and affective loading (e.g., rating of sleep self-efficacy; distress concerning one's sleep problem). Correlations between adjustment and sleep/wake parameters were generally nonsignificant.

Patterns of correlations suggest that daytime sleepiness and fatigue are more clearly associated with depression and with the absence of positive cognitions and affect; correlations between daytime functioning scores and "objective" sleep parameters were non-significant. This pattern was manifested in scores of both Good and Poor Sleepers.

Experienced difficulty falling asleep and associated distress were related to nocturnal sleep/wake variables and to anxiety.

Linear regression analyses indicate (a) that impaired daytime functioning was best predicted by depression, (b) that difficulty falling asleep was best predicted by total nocturnal sleep and awake times and to a lesser extent by anxiety, and (c) that sleep distress was best predicted by anxiety, with total nocturnal sleep and awake times and depression being lesser contributing predictors.

Discussion and Conclusions

Our results demonstrate that there are at least three aspects of the insomnia complaint: difficulty sleeping, distress about the problem, and "daytime sequelae". Our data suggest that the insomnia complaint itself is multifaceted and that cause-effect relationships differ, depending on the aspect under consideration. For example, when difficulty falling asleep and getting back to sleep were considered, the best predictors were actual times spent asleep; distress about sleep problem, was best predicted by anxiety. Daytime fatigue and sleepiness, which are commonly attributed to sleep deprivation, were, in fact, better predicted by low levels of depression than by either sleep or wake times or by anxiety related to sleep. These associations were equally evident in good and poor sleepers, raising the possibility that what are generally considered "daytime sequelae" of the insomnia problem may, in fact, reflect low, sub-clinical levels of depression.

The manifestation of these separable aspects of the insomnia complaint, as well as their associated predictors, have important implications for therapeutic effectiveness. For example, daytime fatigue may be best treated by addressing low level depression, rather than by trying to increase sleep time. High distress over the sleep problem may respond to anxiety management, leaving experienced difficulty falling asleep and getting back to sleep as the only aspect of the insomnia complaint where total sleep and wake times must be addressed directly.