JMIR Publications

ABSTRACT

Background:

Insomnia is a prevalent sleep disorder affecting millions worldwide, with significant impacts on daily functioning and quality of life. While traditionally assessed through subjective measures like the Insomnia Severity Index (ISI), the advent of wearable technology has enabled continuous, objective sleep monitoring in natural environments. However, the relationship between subjective insomnia severity and objective sleep parameters remains unclear, particularly in real-world settings.

Objective:

This study aims to (1) explore the relationship between subjective insomnia severity, as measured by ISI scores, and objective sleep parameters obtained through wearable devices; (2) determine whether subjective perceptions of insomnia align with objective measures of sleep quality and quantity; and (3) identify key psychological and physiological factors contributing to the severity of subjective insomnia complaints.

Methods:

A total of 250 participants, including both individuals with insomnia and normal sleepers aged 19-70, were recruited from March 2023 to November 2023. Participants were grouped based on ISI scores: no insomnia, mild, moderate, and severe insomnia. Data collection involved subjective assessments through self-reported questionnaires (e.g., ISI, State-Trait Anxiety Inventory, PHQ-9) and objective measurements using wearable devices (Fitbit Inspire 1 or 2) that monitored sleep parameters, physical activity, and heart rate. The participants also used a smartphone application for ecological momentary assessment, recording daily alcohol consumption, caffeine intake, exercise, and stress. Statistical analyses, including Kruskal-Wallis tests and ANOVA, were used to compare groups on subjective and objective measures.

Results:

Results indicated no significant differences in general sleep structure (e.g., total sleep time, REM sleep time, light sleep time) among the insomnia groups (mild, moderate, and severe) as classified by ISI scores. Interestingly, participants in the no-insomnia group had longer total awake times and lower sleep quality compared to the insomnia groups. Among the insomnia groups, no significant differences were observed regarding sleep structure, suggesting similar sleep patterns regardless of insomnia severity. Additionally, the insomnia groups showed significantly lower circadian rhythm amplitude, as measured through heart rate, compared to the no-insomnia group. There were also significant differences among the insomnia groups in terms of stress levels, dysfunctional beliefs about sleep, and symptoms of restless leg syndrome (RLS), with higher severity associated with higher scores in these factors. Contrary to expectations, no significant differences were observed in caffeine and alcohol consumption between the groups. These findings suggest that subjective insomnia severity may not directly reflect objective sleep structure but may be influenced by psychological and circadian factors.

Conclusions:

The findings demonstrate a discrepancy between subjective perceptions of insomnia severity and objective sleep parameters, suggesting that factors beyond sleep duration and quality may contribute to subjective sleep complaints. Psychological factors, such as stress, dysfunctional sleep beliefs, and symptoms of RLS, appear to play significant roles in the perception of insomnia severity. These results highlight the importance of considering both subjective and objective assessments in the evaluation and treatment of insomnia and suggest potential avenues for personalized treatment strategies that address both psychological and physiological aspects of sleep disturbances. Clinical Trial: Clinical Research Information Service (CRIS) KCT0009175