Cosby - Season 4 Episode 21 A Long Night's Journey

Hilton suffers from insomnia for several days, falling asleep during the day at inopertune moments, causing Erica and Ruth embarassment. When Hilton refuses to attend a sleep clinic, Griffin offers to set up a video camera in the Lucas' bedroom to record the night's activity to find the cause of Hilton's sleeplessness. The next morning, when the family gathers to watch the tape, no one is more surprised than Ruth to see that it's her snoring and kicking Hilton in her sleep that keeps him awake.