Yes, and they do not have eyelids! So yes, they need darkness since they cannot close their eyes. I don't worry about my blind boy getting light in his tank from my room at night or my male VT or my brothers fish (my three "foster" fish, not bettas though). His fish hide either in the gravel or decor and my VT hides behind his filter when he sleeps, so sometimes I turn the room lights on after the tank lights go out, but I do cover the front of my sorority tank at night so that it stays dark when I have the room lights on or when the sun rises in the morning and makes my room a tiny bit lighter.
I have all my fish tanks on a light timer. They need a consistent schedule of 8-12 hours of light per day. If they get too much light, they can get stresses because of lack of sleep, but I have noticed that dim lighting usually does not wake them.
I'm actually very adamant about putting my fish to bed. I've yelled at my mom before for coming into my room in the morning and turning on the light because I didn't want her to wake my fish from their rest!! Lol.
Edit: I agree with the above poster about them acting strange when you wake them up! When I first upgraded my VT to his five gallon, I started to realize that he slept behind the filter, but there were a few times I checked on him in the morning and he had himself so well hidden that I freaked out and turned on his lights and I "startled" him awake and he was almost acting drunk (you know that disoriented feeling you get in the morning when someone suddenly turns on a bright light?) I thought he was sick, but later realized that I just woke him up from a deep sleep, lol.
Last edited by AyalaCookiejar; 04-05-2013 at 12:38 AM.