• Insomnia may be associated with a sleep-induced apnea syndrome in nonobese patients who snore. The "central" type of apnea appears to be predominant in this population, in opposition to Pickwickian and nonobese hypersomniacs. An abnormal "swallowing reflex syndrome," also induced by sleep, may be a differential diagnosis. Sleeping pills that are central nervous system depressants should be cautiously prescribed for patients with such syndromes.
Guilleminault C, Eldridge FL, Phillips JR, Dement WC. Two Occult Causes of Insomnia and Their Therapeutic Problems. Arch Gen Psychiatry. 1976;33(10):1241-1245. doi:10.1001/archpsyc.1976.01770100103010