Actor Alan Alda has revealed that one of the earliest signs of his Parkinson’s disease was something he noticed while sleeping—not the tremors or slowed movement many people associate with the condition. The M*A*S*H and The West Wing star, who was diagnosed with Parkinson’s in 2015, recently shared the unusual story in an interview with CBS.

Alda recalled having a vivid dream in which someone was attacking him. In the dream, he grabbed what he believed was a sack of potatoes and threw it at the attacker. In reality, he had picked up a pillow and thrown it at his wife, Arlene. Alda later learned that this behavior was consistent with REM sleep behavior disorder, or RBD.

RBD occurs when the normal muscle paralysis that accompanies REM sleep does not work properly, allowing people to act out their dreams by moving, shouting, kicking or punching. The disorder has been strongly associated with Parkinson’s and other neurodegenerative diseases and can sometimes appear years before other neurological symptoms. However, having RBD does not mean someone will definitely develop Parkinson’s.

Research shows why doctors pay attention to the condition. One long-term study found that people with isolated RBD had a risk of developing a neurodegenerative disorder of about 33% after five years, 76% after 10 years and 91% after 14 years. Alda has continued to approach Parkinson’s with humor, saying laughter remains an important part of his life. He and Arlene are also approaching 70 years of marriage, a milestone he says still brings him plenty of reasons to smile. ❤️