Caillou's Summer Goodnight
S1:E21
1998
IMDb
Caillou's parents are going out, and Grandma's coming over to babysit. Later, it's naptime, and he dozes off. Until Glibert comes and wakes him up. Then he has trouble going back to sleep because it's too bright. Grandma comes up with an idea - a cardboard cutout of the night sky, and Caillou eventually falls asleep.