Understanding Sleep Architecture Can Aid Diagnosis

ORLANDO, FL-More is being learned about sleep and how it relates to otolaryngology. At the recent Combined Otolaryngology Spring Meeting, attendees heard details about how the different stages of sleep affect obstructive sleep apnea (OSA), as well as intriguing findings showing how airway anatomy changes can actually be seen during sleep with use of real-time CT imaging.

To set the stage, at the Triological Society section at the conference, Andrew Kleinberger, BA, a fourth-year medical student at New York University School of Medicine, described details about sleep stages, and presented details of a study that provides some clinical predictors of impaired sleep architecture.

When patients present with sleep-related complaints, and there is a low suspicion of obstructive events, should a sleep study be ordered? This is a common issue in the otolaryngologist’s office, and one that can be resolved if there are some clinical predictors on hand to watch for.

First, Mr. Kleinberger explained that sleep architecture refers to the overall structure of sleep. A standard hypnogram will show that sleep is broken up into stages, alternating between REM and non-REM (stages 1 and 2, or light) [light]) sleep, and stages 3 and 4, or slow-wave sleep. Impaired sleep architecture has less slow-wave sleep and REM sleep-thereby becoming a lighter, less restorative sleep.

In severe obstructive sleep apnea, the length of the slow-wave sleep can actually be completely obliterated, and the REM is decreased, with a compensatory increase in stage 2 and light sleep, he said.

Implications for the Otolaryngologist

For the otolaryngologist, sleep issues are important because sleep-related complaints are common, plus sleep architecture has been shown to be associated with sleep-disordered breathing.

But not all sleepiness indicates obstruction. Impaired sleep architecture can be a marker for non-sleep-disordered breathing conditions such as smoking and alcohol use, comorbid psychiatric and system illnesses, or other stressors, Mr. Kleinberger said.

When Should Sleep Studies Be Done?

To help resolve the question of when patients should be sent for sleep studies, a prospective study was done of 211 consecutive patients who underwent overnight polysomnography at a university sleep disorders center. Patients were excluded if a sleep study was ordered for suspicion of either a central sleep disorder, such as insomnia or narcolepsy, or periodic limb movement disorder. They were also excluded if they had a known diagnosis of OSA, or were undergoing polysomnography for the purposes of conducting a continuous positive airway pressure (CPAP) titration.