Sham sleep feedback delivered via actigraphy biases daytime symptom reports in people with insomnia: Implications for insomnia disorder and wearable devices.

This study investigated whether providing sham feedback about sleep to individuals with insomnia influenced daytime symptom reports, sleep-related attentional bias and psychomotor vigilance. Sixty-three participants meeting DSM-5 criteria for insomnia disorder were recruited from the community. Following baseline assessments and actigraphy briefing, participants were randomised to receive next-day sham feedback on sleep quality ("positive" vs. "negative" sleep efficiency condition). Feedback was delivered at habitual rise-time using an integrated actigraphy-diary watch to simulate wearable device behaviour. Participants completed symptom reports immediately before receiving feedback, and at 12:00 and 15:00 hr, using the experience sampling method. Following this they returned to the laboratory in the evening to complete symptom reports and computerised tests of sleep-related attentional bias and basic psychomotor vigilance. Participants randomised to negative feedback (n = 32) evidenced impaired daytime function (decreased alert cognition [d = 0.79], increased sleepiness/fatigue [d = 0.55]) in the evening compared with those given positive feedback (n = 31). Within-day trajectories revealed that the positive-feedback group, relative to the negative-feedback group, displayed a significantly greater increase in positive mood and alert cognition (from rise-time to 12:00 hr), and significantly greater decrease in sleepiness/fatigue. There were no significant between-group differences on measures of sleep-related attentional bias [d = 0.20] or psychomotor vigilance [d = 0.12]. This controlled experiment shows that sham feedback about sleep biases appraisal of daytime symptoms, highlighting a pathway connecting sleep misperception with daytime features of insomnia. Findings have important implications for wearable devices that claim to measure "objective" sleep yet may provide inaccurate data relative to gold-standard measurement.