Impact of sleep duration and chronotype on cardiac structure and function: the UK Biobank study.

BACKGROUND: Sleep duration and chronotype have been associated with increased morbidity and mortality. We assessed for associations between sleep duration and chronotype on cardiac structure and function.

METHODS: UK Biobank participants with CMR data and without known cardiovascular disease were included. Self-reported sleep duration was categorized as short (<7 hours/day), normal (7-9 hours/day) and long (>9 hours/day). Self-reported chronotype was categories as 'definitely morning' or 'definitely evening'.

RESULTS: Analysis included 3,903 middle-aged adults: 929 short, 2,924 normal and 50 long sleepers; with 966 definitely-morning and 355 definitely-evening chronotypes. Long sleep was independently associated with lower left ventricular (LV) mass (-4.8, p=0.035), left atrial maximum volume (-8.1%, p=0.041) and right ventricular (RV) end-diastolic volume (-4.8%, p=0.038) compared to those with normal sleep duration. Evening chronotype was independently associated with lower LV end-diastolic volume (-2.4%, p=0.021), RV end-diastolic volume (-3.6%, p=0.0006), RV end systolic volume (-5.1%, p=0.0009), RV stroke volume (RVSV -2.7%, p=0.033), right atrial maximal volume (-4.3%, p=0.011) and emptying fraction (+1.3%, p=0.047) compared to morning chronotype. Sex interactions existed for sleep duration and chronotype and age interaction for chronotype even after considering potential confounders.

CONCLUSIONS: Longer sleep duration was independently associated with smaller LV mass, left atrial volume and RV volume. Evening chronotype was independently associated with smaller LV and RV and reduced RV function compared to morning chronotype. Sex interactions exist with cardiac remodeling most evident in males with long sleep duration and evening chronotype. Recommendations for sleep chronotype and duration may need to be individualized based on sex.