December 16, 2025

Circadian System Disruptions in Sleep Apnea Increase the Risk of Nighttime Cardiac Events

3 minutes

New research shows that people with untreated sleep apnea experience a sharp nighttime drop in blood vessel function driven by the circadian system, increasing vulnerability to heart attacks and other cardiac events
In a tightly controlled sleep-lab study, participants' arteries showed their worst ability to dilate around 3:00 a.m., revealing an 82% decline in vascular function during the biological night
This impairment persisted even after adjusting for blood flow, sleep quality, and apnea severity, confirming the circadian system — not behavior or breathing events — directly weakens vascular health at night
The findings help explain why people with sleep apnea experience more nighttime cardiac events, contrasting with the general population's morning peak in heart attacks and sudden cardiac death
Researchers emphasize that understanding circadian timing may help refine cardiovascular treatments for sleep apnea patients, including optimizing medication schedules to enhance nighttime vascular protection

...more

By Dr. Mercola

4.6

14871,487 ratings

December 16, 2025

3 minutes

New research shows that people with untreated sleep apnea experience a sharp nighttime drop in blood vessel function driven by the circadian system, increasing vulnerability to heart attacks and other cardiac events
In a tightly controlled sleep-lab study, participants' arteries showed their worst ability to dilate around 3:00 a.m., revealing an 82% decline in vascular function during the biological night
This impairment persisted even after adjusting for blood flow, sleep quality, and apnea severity, confirming the circadian system — not behavior or breathing events — directly weakens vascular health at night
The findings help explain why people with sleep apnea experience more nighttime cardiac events, contrasting with the general population's morning peak in heart attacks and sudden cardiac death
Researchers emphasize that understanding circadian timing may help refine cardiovascular treatments for sleep apnea patients, including optimizing medication schedules to enhance nighttime vascular protection

...more