RSWA on polysomnography is most strongly associated with which condition?

• A. REM sleep behavior disorder and some neurodegenerative diseases.
• B. Insomnia and jet lag.
• C. Narcolepsy without cataplexy.
• D. Restless legs syndrome.

Answer: (A)

REM sleep without atonia on polysomnography means there’s muscle activity during REM sleep when the body should be paralyzed. This pattern is the hallmark of REM sleep behavior disorder, where dream enactment occurs because the typical REM atonia is lost or reduced.

Because of this, RSWA is most strongly linked to REM sleep behavior disorder. RBD is also a telltale sign of underlying neurodegenerative diseases, especially the synucleinopathies like Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy. So the presence of RSWA on polysomnography points you toward REM sleep behavior disorder and raises concern for these neurodegenerative processes.

The other conditions listed—insomnia, jet lag, narcolepsy without cataplexy, and restless legs—do not feature RSWA as their defining sleep-motor finding. Narcolepsy can involve abnormal REM features, but not the characteristic loss of atonia during REM that defines RSWA. Restless legs and jet lag are more about limb movements or circadian disruption, not REM-specific atonia loss.