Hi, I think they become pale once the light was off aft 3am & recover back aft 9am when the surrounding environment becomes brighter. Also I notice that they dun take food during this period. I feed twice a day, once bef I go to work at 8am & another at around 8pm. Only my molly & guppies will eat in the morning, neons will not eat & can be seen to be very inactive. But at nite, they will have a very good appetite.