The natural tendency when treating patients with obstructive sleep apnea is to overlook other sleep disorders that can contribute to symptoms like daytime sleepiness and fatigue. Insomnia is technically the most common sleep disorder, although in reality the term “insomnia” refers to a group of sleep issues. Recent studies have examined the differences between subtypes of insomnia, separating those with difficulty falling asleep (initial insomnia), difficulty maintaining sleep (middle insomnia), and early morning awakening (late insomnia).
Many patients with obstructive sleep apnea also suffer from insomnia. In my mind, the most challenging aspects are determining (1) whether any symptoms are related more to sleep apnea or insomnia and (2) whether the insomnia will improve, worsen, or remain unchanged with treatment of the sleep apnea. An Icelandic study published in the December 2013 issue of the medical journal SLEEP evaluated the connection between obstructive sleep apnea and the various subtypes of insomnia to address the second question. Iceland is home to some outstanding sleep research, due to committed teams that provide excellent care and a centralized approach to treating all patients with sleep apnea at a single center in Reykjavik, the capital.
Sleep apnea treatment can improve some kinds of insomnia
Among 705 patients with sleep apnea, before treatment the proportions with early, middle, and late insomnia were 15%, 60%, and 27%, respectively. This agreed with expectations, as sleep apnea can cause arousals from sleep in the middle of the night. Early and late insomnia was associated with a lower chance (about half the odds) of tolerating positive airway pressure. Both types of difficulty sleeping can make patients more aware of the potential challenges of positive airway pressure, so this was not particularly surprising. What was surprising was that middle insomnia was not associated with more difficulty tolerating positive airway pressure and, interestingly, improved with positive airway pressure.
Although I only rarely treat patients with positive airway pressure therapy myself–instead referring them back to their sleep medicine physician–this study has important implications. Just as middle insomnia improves with positive airway pressure, so too should it improve with surgery that achieves a successful outcome. In my personal experience, I have seen many patients with all types of insomnia improve after surgery, but I have not looked at my own results as carefully and scientifically as was done in this study.