He only sleeps an average of 2–3 hours.
Isayama has said that if he could say one thing to Levi, it would be, "Go quickly to sleep," as Levi suffers from slight bouts of insomnia. Also, Levi does not change clothes before going to sleep, as it is such a non-event for him. Rather than sleeping in a bed, Levi just sleeps in his chair.
