Cardiovascular autonomic dysfunction in insomnia patients with objective short sleep duration

Area of Science:

• Cardiology
• Sleep Medicine
• Psychophysiology

Background:

• Insomnia presents with two phenotypes: one with near-normal sleep duration linked to psychological symptoms, and another with short sleep duration associated with cardiometabolic issues.
• Reduced heart rate variability (HRV) is implicated in cardiometabolic disease, but its association with different insomnia phenotypes is understudied.

Purpose of the Study:

• To investigate cardiovascular function, specifically heart rate variability, in adults with chronic insomnia based on objective sleep duration phenotypes.
• To compare parasympathetic activation and sympathovagal balance between insomnia patients with objectively short sleep duration and those with near-normal sleep duration.

Main Methods:

• 180 adults with chronic insomnia underwent polysomnography for objective sleep duration assessment (total sleep time) and 2-week sleep diaries for subjective duration.
• Participants were categorized into groups with objective sleep duration <6 hours or ≥6 hours.
• Electrocardiogram data from polysomnography were analyzed for heart rate and HRV during N2 and REM sleep, including high-frequency (HF) power and the low- to high-frequency ratio (LF/HF).

Main Results:

• Patients with objectively short sleep duration (<6 hours) demonstrated significantly reduced high-frequency power (p < .05), indicating dampened parasympathetic activation.
• These patients also exhibited an elevated LF/HF ratio (p = .036), signifying increased sympathovagal imbalance, and a trend towards higher heart rate (p = .051).
• No significant differences in cardiovascular measures were found when using subjective sleep duration for group categorization.

Conclusions:

• Objective short sleep duration in insomnia is associated with detrimental cardiovascular autonomic regulation, characterized by reduced parasympathetic tone and increased sympathetic-parasympathetic imbalance.
• These findings underscore the physiological impact of short sleep duration in insomnia and suggest that interventions targeting sleep may have cardiovascular benefits.
• The study highlights the critical importance of differentiating insomnia phenotypes based on objective sleep measures for understanding associated health risks.