Case-control study of subjective and objective differences in sleep patterns in older adults with insomnia symptoms.

Older adults have high prevalence rates of insomnia symptoms, yet it is unclear if these insomnia symptoms are associated with objective impairments in sleep. We hypothesized that insomnia complaints in older adults would be associated with objective differences in sleep compared with those without insomnia complaints. To test this hypothesis, we conducted a cross-sectional study in which older adults with insomnia complaints (cases, n=100) were compared with older adults without insomnia complaints (controls, n=100) using dual-night in-lab nocturnal polysomnography, study questionnaires and 7 days of at-home actigraphy and sleep diaries. Cases were noted to have reduced objective total sleep time compared with controls (25.8 ± 8.56 min, P=0.003). This was largely due to increased wakefulness after sleep onset, and not increased sleep latency. When participants with sleep-related breathing disorder or periodic limb movement disorder were excluded, the polysomnography total sleep time difference became even larger. Cases also had reduced slow-wave sleep (5.10 ± 1.38 min versus 10.57 ± 2.29 min, effect size -0.29, P=0.04). When comparing self-reported sleep latency and sleep efficiency with objective polysomnographic findings, cases demonstrated low, but statistically significant correlations, while no such correlations were observed in controls. Cases tended to underestimate their sleep efficiency by 1.6% (±18.4%), while controls overestimated their sleep efficiency by 12.4% (±14.5%). In conclusion, we noted that older adults with insomnia complaints have significant differences in several objective sleep findings relative to controls, suggesting that insomnia complaints in older adults are associated with objective impairments in sleep.