Subjective-objective sleep discrepancy among older adults: associations with insomnia diagnosis and insomnia treatment

Abstract

Discrepancy between subjective and objective measures of sleep is associated with insomnia and increasing age. Cognitive behavioural therapy for insomnia improves sleep quality and decreases subjective-objective sleep discrepancy. This study describes differences between older adults with insomnia and controls in sleep discrepancy, and tests the hypothesis that reduced sleep discrepancy following cognitive behavioural therapy for insomnia correlates with the magnitude of symptom improvement reported by older adults with insomnia. Participants were 63 adults >60 years of age with insomnia, and 51 controls. At baseline, participants completed sleep diaries for 7 days while wearing wrist actigraphs. After receiving cognitive behavioural therapy for insomnia, insomnia patients repeated this sleep assessment. Sleep discrepancy variables were calculated by subtracting actigraphic sleep onset latency and wake after sleep onset from respective self-reported estimates, pre- and post-treatment. Mean level and night-to-night variability in sleep discrepancy were investigated. Baseline sleep discrepancies were compared between groups. Pre-post-treatment changes in Insomnia Severity Index score and sleep discrepancy variables were investigated within older adults with insomnia. Sleep discrepancy was significantly greater and more variable across nights in older adults with insomnia than controls, P ≤ 0.001 for all. Treatment with cognitive behavioural therapy for insomnia was associated with significant reduction in the Insomnia Severity Index score that correlated with changes in mean level and night-to-night variability in wake after sleep onset discrepancy, P < 0.001 for all. Study of sleep discrepancy patterns may guide more targeted treatments for late-life insomnia.

Keywords: CBTI; actigraphy; aging; sleep measurement.

Figure 1

Data points represent individuals’ change in Insomnia Severity Index (ISI) total score in relation to the change in minutes of wake after sleep onset (WASO) discrepancy (post- minus pre- treatment values). Negative values indicate a decline from pre- to post-treatment. Individuals who had a greater shift in the direction of reporting less WASO than was objectively measured had a greater reduction in insomnia severity measured by the ISI.

Figure 2

Data points represent individuals’ change in Insomnia Severity Index (ISI) total score in relation to the change in minutes of night-to-night variability in wake after sleep onset (WASO) discrepancy (post- minus pre- treatment values). Negative values indicate a decline from pre- to post-treatment. Individuals who had a greater decline in night-to-night variability in WASO discrepancy had a greater reduction in insomnia severity measured by the Insomnia Severity Index.