Chronic Sleep Irregularity Is Common, Persistent, and Associated With Poorer Sleep Health

Sleep irregularity, characterised by inconsistent sleep duration and timing, is increasingly linked to adverse health outcomes including hypertension. However, the persistence and long-term effects of irregular sleep remain unclear, largely due to short sleep monitoring periods in past studies. This study aimed to examine the chronic, cumulating impacts of irregular sleep on sleep health (sleep duration, efficiency, timing) and blood pressure. We analysed approximately 20 months of under-mattress sleep sensor data from 95,819 global participants. Each person-month of sleep data was classified as 'irregular' if sleep duration variability was ≥ 90 min and sleep midpoint variability was ≥ 60 min (intra-individual standard deviation): thresholds that were previously found to correlate with poor cardiovascular health. Approximately 20% of person-months were classified as irregular by these criteria. Participants with chronic irregular sleep (≥ 75% of months irregular) exhibited 8% lower sleep efficiency, 40 min more wake after sleep onset, and 46% higher odds of hypertension compared to those with regular sleep (0%-25% of months irregular). Irregular sleep patterns were persistent, with over 80% likelihood of continuation after six consecutive irregular months. These findings suggest that chronic sleep irregularity is common, persistent, and associated with poorer sleep quality and elevated blood pressure. This underscores the need for interventions to promote consistent sleep patterns to support cardiovascular health.