In two new studies, researchers found that patients with obstructive sleep apnea (OSA) have higher immediate heart rate variability.
In addition, the greater changes in beat-to-beat intervals are associated with reduced daytime alertness.
The research was conducted by a team from the University of Eastern Finland.
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.
Abnormal respiratory events, be they complete or partial blocking of the airways, often cause repeated oxygen desaturations and interrupted sleep in patients with OSA, leading to abnormal nervous system function.
Abnormal hyper-activation of the sympathetic nervous system affects heart function by increasing OSA 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 OSA 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 OSA.
Two recent studies have explored the immediate effect of respiratory events on heart rate variability, as well as the association of OSA patients’ nocturnal heart rate changes with their alertness.
One study shows that the type and duration of respiratory events has an effect on heart rate and heart rate variability both during and after the event.
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 OSA.
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.
One author is Early Stage Researcher Salla Hietakoste from the University of Eastern Finland.
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