Core body temperature changes before sleep are associated with nocturnal heart rate variability

Area of Science:

• Physiology
• Sleep Science
• Cardiology

Background:

• Core body temperature (CBT) reductions precede and accompany sleep, influencing sleep onset and quality.
• Presleep CBT changes correlate with parasympathetic activity (heart rate variability - HRV).
• Individual variations in presleep CBT decline and their impact on nocturnal HRV are not well understood.

Purpose of the Study:

• To investigate the relationship between individual differences in presleep CBT decline and nocturnal heart rate (HR) and HRV.
• To test the hypothesis that a blunted CBT decline rate is associated with elevated HR and reduced nocturnal HRV in poor sleepers.

Main Methods:

• Overnight polysomnographic sleep studies were conducted in 15 adults with poor sleep.
• Simultaneous recording of electrocardiography (ECG) for HRV and CBT was performed.
• Correlations between presleep CBT rate of change and nocturnal HRV were analyzed.

Main Results:

• A blunted rate of CBT decline was significantly associated with increased HR during N2, N3, and REM sleep stages.
• Reduced presleep CBT decline was also linked to lower HRV across all sleep stages.
• These associations were statistically significant (P < 0.002).

Conclusions:

• Individual differences in presleep thermoregulation are related to nocturnal cardiac autonomic function in adults with poor sleep.
• The findings suggest an overlap between presleep thermoregulatory processes and cardiac autonomic regulation during sleep.
• This highlights the importance of temperature regulation for sleep quality and autonomic health.