My guess would be that he took it off and there are a couple of reasons for that. The first is the thing would probably be uncomfortable especially if he slept on his side or stomach and he would risk damaging the VISOR. The other reason is there was never a mention of an off switch so the device most likely remained active feeding data directly into his brain. There is also the consideration that as an electronic device it probably had to be charged and the best time would be at night while hi was sleeping.
In "The Most Toys", Geordi was shown taking it off to sleep. There was also something early in Star Trek: The Next Generation about it being painful for him to use; and, later on, Doctor Pulaski counsels him about going with cloned implants (ostensibly because they were better); and by Star Trek: First Contact he has newer implants that reside entirely in his ocular cavities; and, by Star Trek: Insurrection, the metaphasic radiation of the Briar Patch had, at least temporarily, given him normal, naturally-produced, eyesight ProfessorTrek 03:44, July 18, 2011 (UTC)
As far as I know, he took it off to sleep (it has been shown at least once and I think twice), but I've never seen it recharging.