I have had to sleep with the sound of a air purifier fan for so long now that I need the sound to sleep. I don't need the air purifier at my new house anymore, but I can't sleep without the sound. I bought the Sleep Therapy about a week ago and so far I actually fall asleep quicker and I am sure I am saving on electricity to run the unit. I have it set to the longest time available of 1 hour. It has settings 15, 30, 45, and 60 minutes. You cannot leave it on longer unless you hit the start button again once it shuts off. My six year old loves to play with all the sounds. His favorite is the heartbeat. I like all the sounds, but use white noise as it is closest to the sound of the fan it is replacing. The volume can go quite loud. No worries about whether or not you will hear the sounds, you should have no problem even from across the room.