During an episode of obstructive sleep apnea (OSA) where the upper airway collapses, the oxygen level in your blood decreases (hypoxia). This is terminated by a sudden arousal or awakening from sleep at which time the oxygen level normalizes. This cyclic decrease in blood oxygen level followed by deoxygenation is a result of increased sympathetic activity in the body. Think ‘flight or fight response’. During this episode of increased activity, the heart rate increases, glucose increases, adrenal glands release norepinephrine and epinephrine among other changes. This is non balanced state. OSA causes increased sympathetic activity which has been proposed as a mechanism behind inflammation and cardiovascular disease.
The good news is that with PAP (Positive Airway Pressure) therapy, reduced sympathetic activity occurs and inflammation decreases which may decrease your risk of cardiovascular disease.
Have you ever wondered why patients with Obstructive Sleep Apnea (OSA) may also be overweight? OSA is present in approximately 40% of obese individuals and about 70% of OSA patients are obese. Could it because their sleep is fragmented frequently at night due to upper airway collapse causing the brain to ‘arouse’ to breath thus causing daytime sleepiness? Maybe? Or are there other mechanisms behind this?
Frequent sleep fragmentation due to OSA as well as sleep restriction disturbs many processes in the body. In particular, levels of our hunger hormone (ghrelin) increases. Increased ghrelin levels will stimulate appetite. In addition, levels of leptin (a protein produced in fat cells) decrease. The primary function of leptin is to send a signal to the brain when you are full. Since leptin levels are low, the brain will not get the signal that you are full. This will cause you to eat more. These 2 processes working against each other will lead to obesity.
The good news is that effective treatment with Positive Airway Pressure (PAP) will normalize these levels.
