Could Stress Cause Sleep Apnea?
Another interpretation is that stress might cause sleep apnea. Researchers forward this explanation in a study of nurses and other medical workers in Wuhan province treating COVID-19 patients. Using questionnaires, researchers evaluated 26 members of the medical staff at a hospital for stress and insomnia. Researchers used pulse oximetry, measured by a pulse oximeter contained in a ring, to estimate sleep apnea levels.
The results showed that ten participants met the criteria for moderate to severe sleep apnea, with an AHI (apnea-hypopnea index) of 15 or greater. They found that people with high-stress levels were about 50% more likely to have sleep apnea than those with lower stress levels.
The researchers used this data to say that the workers’ stress caused their sleep apnea.
Researchers tried to explain how stress might cause sleep apnea by looking at the activation of the hypothalamic-pituitary-adrenal (HPA) axis.
Chronic stress activates the HPA axis, which leads to lighter sleep. This, in turn, leads to upper airway instability, causing it to collapse more often, which causes obstructive sleep apnea by cutting off access to air. The result is hypoxic stress caused by oxygen shortage. This creates a cycle whereby stress leads to sleep apnea which increases stress.
It’s hard to know if this explanation is reasonable. The study is not large enough to make definitive conclusions about the link between stress and sleep apnea. The study design doesn’t help determine which condition causes which. The precise link between the conditions remains a mystery, though it seems definite that there is some link.