Background: Self-reported long habitual sleep durations (≥ 9 h per night) consistently predict increased mortality. We compared objective sleep parameters of self-reported long versus normal duration sleepers to determine whether long sleepers truly sleep more or have an underlying sleep abnormality.
Methods: Older men participating in the Osteoporotic Fractures in Men Study (MrOS) were recruited for a comprehensive sleep assessment, which included wrist actigraphy, overnight polysomnography (PSG), and a question about usual nocturnal sleep duration.
Results: Of the 3134 participants (mean age 76.4 ± 5.6; 89.9% Caucasian), 1888 (60.2%) reported sleeping 7-8 h (normal sleepers) and 174 (5.6%) reported ≥ 9 h (long sleepers). On actigraphy, long sleepers spent on average 63.0 min more per night in bed (P < 0.001), slept 42.8 min longer (P < 0.001), and spent 6.8 min more per day napping (P = 0.01). Based on PSG, the apnea hypopnea index, periodic limb movement index, arousal index, and sleep stage distribution did not differ. After adjusting for differences in demographics, comorbidities, and medication usage, self-reported long sleepers continued to spend more time in bed and sleep more, based on both actigraphy and PSG. Each additional 30 min in bed or asleep as measured by actigraphy increased the odds of being a self-reported long-sleeper 1.74-fold and 1.33-fold, respectively (P < 0.001 for both).
Conclusions: On objective assessment, self-reported long sleepers spend more time in bed and more time asleep than normal duration sleepers. This is not explained by differences in comorbidity or sleep disorders.
Keywords: Sleep duration; actigraphy; long sleeper; polysomnography.