Alan Alda was already a celebrated actor when an unusual moment during sleep gave him a clue that something was wrong. The MASH* and The West Wing star, now 90, was diagnosed with Parkinson’s disease in 2015, but his earliest warning sign had nothing to do with the tremors many people associate with the condition. Instead, Alda discovered that he was physically acting out his dreams. During one particularly vivid dream, he believed someone was attacking him and grabbed what he thought was a sack of potatoes. In reality, he had picked up a pillow and thrown it at his wife, Arlene. Alda later learned that the strange behavior was known as REM sleep behavior disorder, or RBD, a condition in which the normal muscle paralysis during vivid dreaming does not work properly.

RBD can cause people to move, shout, kick or punch while asleep, and doctors recognize it as a possible early warning sign of certain neurological diseases, including Parkinson’s, although having RBD does not mean someone will necessarily develop Parkinson’s. For Alda, the discovery eventually became part of a much larger health journey. He has also spoken publicly about living with face blindness and the everyday challenges Parkinson’s can bring, including difficulty controlling his hand while using a computer. Yet he continues to approach those frustrations with the humor that has defined much of his career. Alda told CBS that when Parkinson’s interferes with his daily life, he tries to find something funny about the situation and share it with Arlene. The couple, who have been married for nearly 70 years, have three daughters and eight grandchildren, and Alda says laughter was part of what first brought them together. His story offers a reminder that some health changes can appear in surprisingly ordinary moments, even during sleep.