Actigraphy prior to MSLT: nighttime total sleep time predicts sleep onset latency.

STUDY OBJECTIVES To evaluate the clinical utility of actigraphy as compared to sleep questionnaires prior to the Multiple Sleep Latency Test (MSLT) in a sleep disorders clinic population. METHODS Twenty-eight clinically referred participants (mean age 42.3±18.8) completed the study protocol. On day 1, participants completed questionnaires: Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), Visual Analog Scale (VAS affect, vigor), Patient Health Questionnaire (PHQ-9), and Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-sf). On days 1-8, participants wore an actigraph and completed a sleep diary to assess mean nighttime and mean daytime total sleep time (TST) and sleep efficiency (SE) or sleep percent. On day 9, participants repeated the ESS and completed an MSLT. Correlations assessed mean MSLT sleep onset latency (MSLT-SOL) vs. actigraphy, sleep diary, and questionnaires. Chi-square analyses assessed abnormal MSLT-SOL (≤8 minutes) or daytime sleepiness (ESS ≥10) and referral question (i.e. sleep-disordered breathing vs. hypersomnolence disorder). RESULTS Mean MSLT-SOL was correlated with nighttime TST assessed via both actigraphy and diary, but not with questionnaires. Significant correlations emerged for ESS score day 1 vs. 9, actigraphy vs. sleep diary mean nighttime TST, and PSQI vs. mean sleep diary SE. There was no significant relationship between mean MSLT-SOL and referral question. CONCLUSIONS Our finding that TST measured by actigraphy was associated with MSLT-SOL suggests it is useful in informing interpretation of MSLT findings; however, it does not appear to be a viable substitute for MSLT for the measurement of objective sleepiness in clinical settings.