Yes.. Theta is a transitional brainwave state between relaxed (alpha) and asleep (delta) . It is also the brainwave state that make us drive our car from here to there and not remember how we got there. It is the state that hypnotists strive to get there subjects to for auto-suggestion. It is the 'day-dream' state and it is inherently tied to sleep. Ergo, sleeping pills are called hypnotics... and so on.