Interrupted Breathing During Sleep Affects Brain Neurons That Regulate Heart Rate

People with common sleep breathing disorder have reduced activity among neurons that play a key role in keeping heart rate low, a new study suggests.

Researchers at George Washington University USA claim that in obstructive sleep apnoea (OSA), the neurons in the brainstem that regulate heart rate undergo a diminished activity. This diminished neuronal activity further triggers increased heart rate, blood pressure and also the risk of adverse cardiovascular events in OSA patients.

One of the common cardiovascular disease is OSA, which occurs is mostly men than women (24 percent men and 9 percent females). Due to this, the person experiences repetitive interruptions of breathing while sleeping.  Most often the person comes to a lighter state of sleep or brief wakefulness due to the lack of oxygen during this episode. Frequent interrupted breathing and arousal from sleep occurs at least once per minute.

Dr David Mendelowitz, who led the study at says, "Lack of sleep leaves the mind and body tired, leading to poor mental and physical performance, and if untreated OSA increases a person's risk of developing hypertension and irregular heartbeats. Therefore it is very important that we have discovered some of the underlying mechanisms that could injure the heart and other cardiovascular tissues."

The researchers examined this mechanism in rats by replicating OSA for four weeks and then analysing the blood pressure, heart rate and synaptic activity in parasympathetic neurons that regulate heart rate.

"Our study shows that progression of blunted cardiovascular reflexes is accompanied, and likely maintained by, inhibition of neurons in the brainstem that protect the heart and normally maintain a low resting heart rate. This study would predict that patients who have OSA, and also take sleep medicines, might be at heightened risk for an exaggerated reduction of essential neuronal activity that protects the heart," he said.

The finding was documented in the journal of Physiology.