Actigraphy-derived sleep disturbances and long-term circadian HRV alterations in asthma

Asthma is frequently associated with nocturnal symptom worsening and autonomic imbalance; however, the relationship between sleep characteristics and circadian heart rate variability (HRV) remains incompletely understood. This study investigated sleep parameters, circadian HRV rhythmicity and their associations in 50 male patients with stable asthma and 45 age-matched healthy controls. Actigraphy-derived sleep parameters were recorded over 5–7 days, and 72-hour ambulatory ECG recordings were used to derive 24-hour HRV profiles. Sleep measures included sleep duration, latency, efficiency, fragmentation, activity indices and total rest time. Circadian rhythms of heart rate and HRV indices were assessed using cosinor analysis. Compared with controls, asthmatic patients exhibited longer sleep latency, greater nocturnal activity, increased sleep fragmentation and longer sleep duration, indicating poorer sleep quality. Circadian rhythmicity was preserved at the group level in both groups; however, asthma was associated with reduced consistency of rhythmic expression and selective alterations in HRV, particularly reduced very-low frequency (VLF) power. Although between-group differences in rhythm parameters were not statistically significant after correction for multiple comparisons, effect size analysis indicated a moderate-to-large reduction in VLF, suggesting altered long-term autonomic regulation. Overall, asthma is characterized by impaired sleep parameters and selective circadian autonomic alterations, with potential implications for chronotherapy-based interventions.