Obstructive sleep apnea affects approximately 1 billion people worldwide.
It is one of the most prevalent sleeping disorders, putting a great strain on national economies and on public health.
In two recent studies from the University of Eastern Finland, researchers found that patients with sleep apnea have higher immediate heart rate variability.
In addition, the greater changes in beat-to-beat intervals are linked to reduced daytime alertness.
The study findings are published in Scientific Reports and ERJ Open Research. One author is Salla Hietakoste.
In patients with sleep apnea, abnormal respiratory events often cause repeated oxygen desaturations and interrupted sleep, leading to abnormal nervous system function.
Abnormal hyper-activation of the sympathetic nervous system affects heart function by increasing sleep apnea patients’ heart rate and by reducing their long-term heart rate variability.
These changes have been shown to strongly increase the risk of heart diseases.
In addition, hyper-activation of the sympathetic nervous system can prevent patients with sleep apnea from getting enough deep, restorative sleep, which is why they often feel tired and less alert during the day.
Hyper-activation of the sympathetic nervous system can keep the body in a state of alertness over the long term despite sufficient deep sleep, and this can be seen in, e.g., elevated daytime heart rate in patients with sleep apnea.
In the studies, the team explored the immediate effect of respiratory events on heart rate variability, as well as the association of sleep apnea patients’ nocturnal heart rate changes with their alertness.
One study shows that the type and duration of respiratory events have an effect on heart rate and heart rate variability.
A longer duration of a respiratory event caused greater changes in heart rate as well as higher ultra-short-term heart rate variability, and both of these changes were greater during complete obstruction of the airway.
The other study found that changes in pulse rate measured via finger photoplethysmogram were linked to performance in the psychomotor vigilance task (PVT) in patients with sleep apnea.
Patients who performed poorly in the PVT had a much higher night heart rate.
In both studies, the findings were more pronounced in men.
The findings suggest that the abundance of data available from current clinical sleep studies could be utilized more extensively in the future.
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