It might of been, there's been no accounts from passengers that the room was open. It's likely that it was closed though. They closed most of the A-deck public rooms (beside the Smoking Room) for cleaning. I suspect that the stewards would have locked the door to the R & W Room, in progress of locking the lounge doors. I don't really know when the stewards started waking the passengers. Hopefully some one else will chime in on this detail.
The official time for closing of the Lounge was 11:30pm. I think the reading room would have been closed earlier, I'm not sure, but probably at 11pm. The Smoke room was supposed to have officially closed at 12 midnight.
I'm not sure if the R&W room was ever reopened. It might have, as was the lounge, but perhaps the crew kept it closed so as to not have the passengers in too many places on a sinking ship. I don't recall any accounts of passengers being in the R&W room after the accident, but that does not mean that is was definitely closed.
As for when the passengers were woken up, Brandon is right in saying, that it was when the order for boats and lifebelts was given. There were of course plenty of passengers already awake before than, but about 12 midnight, or soon after that the order was given. So stewards began to walk around and wake passengers.