According to experiments, they can't "sleep" in space

YOYOS

Think of a classic toy that relies on gravity to return to your hand—astronauts found it useless without Earth's pull.

This clue plays on the idea that yo-yos don’t work properly in zero gravity—they can’t "sleep" (the term for when a yo-yo spins at the end of its string) because there’s no gravity to pull them back. Experiments in space have shown yo-yos just float uselessly when tossed, making them a fun example of how everyday objects behave differently outside Earth’s atmosphere. The word "sleep" here is a clever nod to yo-yo terminology, not actual rest.