KL Lichstein, BW Riedel, et al (Univ of Memphis, Tenn; Methodist healthcare, Memphis, Tenn)
Occult Sleep Apnea in a Recruited Sample of Older Adults with Insomnia.
J Consult Clin Psychol 67: 405-410, 1999
Sleep apnea is best differentiated from insomnia by polysomnography, however most patients complaining of insomnia do not undergo this costly investigation.
In the study quoted below polysomnography was performed in older patients complaining of insomnia. To estimate the incidence of sleep apnea in the population, the subject were 80 volunteers, more than 59 years of age primarily thought to have diagnosis of insomnia without obvious sleep apnea or period limb movement or restless leg syndrome.
Findings- Of the 80 subjects, 23 had apnea hypopnea index (AHI) or 15 or less and 34 had an apnea hypopnea index of 5 or less. Thus met the criteria for sleep apnea.
Depending on the apnea hypopnea index cutoff used almost 29% and 43% of older adults complaining of insomnia have sleep apnea. This seems to be a signficantly high rate of occult obstructive sleep apnea in the older age group adults presenting with insomnia.