These massive mammals fascinate me. I’ve seen many a dorsal fin and tail, but few full bodies coming out of the water. Usually when you see the flip of a tail they are going deep. I wanted to know if they sleep, so did a bit of research and yes, they will sleep/rest at any time day or night by floating in either a horizontal position or head down, tail up. They need less oxygen at rest, so can stay immobile for a few hours. Amazing right?