SAN DIEGO—As if having insomnia or sleep-disordered breathing isn’t challenging enough, some patients turn out to have complex insomnia, a combination of moderate or severe insomnia disorders and specific symptoms of sleep-disordered breathing.
“This overlap of insomnia and obstructive sleep apnea is interesting,” said David N. Neubauer, MD, at the annual US Psychiatric and Mental Health Congress.
The Prevalence of Complex Insomnia
According to a study of 801 primary care outpatients with no sleep disorder history who presented for complaints unrelated to sleep, 82% had at least one insomnia symptom, 36% met criteria for insomnia disorder, 60% had at least one symptom of sleep-disordered breathing, 51% had at least one insomnia symptom and one symptom of sleep-disordered breathing, while 17% had potential complex insomnia. Several other studies have demonstrated a strong prevalence of insomnia in patients with obstructive sleep apnea (OSA), “which is not that surprising,” said Dr. Neubauer, Associate Director of the Johns Hopkins Sleep Disorders Center in Baltimore.
At least three sleep studies conducted in older patients with insomnia, however, found a high prevalence of OSA. A study of 394 postmenopausal women from ages 55 to 70 found that 67% had an apnea–hypopnea index (AHI) of 5 or greater.
In a separate trial, veterans in the Los Angeles area who were at least age 60 and had seen a Veterans Affairs outpatient provider in the past two years were recruited for an insomnia behavioral intervention trial. To be eligible for the trial, participants had to have had a sleep disturbance with daytime consequences for at least three months. People with a history of sleep apnea diagnosis or treatment were excluded. Interventions included questionnaires, a phone interview, and in-home testing with the WatchPAT system, a portable device from Itamar Medical that can help diagnose sleep apnea. The mean age of the 435 community-dwelling participants was 72, and their mean BMI was 28 kg/m2. The researchers found that the prevalence of OSA, defined as an AHI of 15 or greater, was 47%.
In another study conducted at Stanford University, researchers set out to evaluate the impact of a cognitive behavioral intervention in people with insomnia and major depression. The screening consisted of a phone interview, in-person screening, and an overnight polysomnography test. The mean age of the 51 people who completed the screening was 48, and 57% of participants were female.
The researchers found that 69% of patients had an AHI of 5 or greater. Of those patients, 29% had an AHI between 5 and 15, 24% had an AHI between 15 and 25, while 16% had an AHI of greater than 25. “It must have been frustrating for these researchers to get a clean insomnia population because so many ended up having sleep apnea as part of their underlying problem,” Dr. Neubauer said.
The Role of OSA in Insomnia
Clinicians might think that the worse the OSA, the worse the insomnia, “but that’s not necessarily the case, because a lot of people with severe OSA are just really sleepy, and they’re sleeping through the next day,” Dr. Neubauer said. Patients with a combination of OSA and insomnia symptoms “tend to be some of the people with milder sleep apnea, or those who are under the radar, who wouldn’t even get diagnosed with OSA, but they have that same physiologic process of some inspiratory flow limitation.” This subset of patients might meet criteria for upper airway resistance syndrome, which was first described in 1993 and is characterized by repetitive increases in resistance to airflow, increased respiratory effort, absence of oxygen desaturation, brief sleep state changes or arousals, and daytime somnolence.
“In the sleep community, the diagnosis of upper airway resistance syndrome is somewhat debatable, because some people think that if you don’t have absolute apnea events, they don’t count [as a sleep disorder],” Dr. Neubauer said. “But there are a lot of people who feel that these under-the-radar events may still have a significant effect on sleep.”
Compared with patients with OSA, those with upper airway resistance syndrome tend to be younger, female, and have a lower BMI. In addition, he said, sleep-onset insomnia is common, and the condition is associated with functional somatic syndromes, such as headache, irritable bowel syndrome, gastroesophageal reflux, rhinitis, and orthostatic intolerance.
Drugs, Insomnia, and Somnolence
A recent analysis of 14 second-generation antidepressants based on FDA data and pharmaceutical company records found that the five most likely to cause insomnia, compared with placebo, are bupropion, desvenlafaxine, sertraline, fluvoxamine, and fluoxetine. Furthermore, the five most likely to cause somnolence, compared with placebo, are fluvoxamine, mirtazapine, reboxetine, paroxetine, and desvenlafaxine.