HELP! Cant remember the name of a movie i want to watch again!

So I cant remember the whole plot. There was some weird scientific expirement where this woman was plugged into a machine which took her to this room. She was locked up there for X amount of days (100 if I remember right) and the days countdown was up on this massive screen in the room. But in reality it was only like a few minutes. It also had something to do with an accident that happened on a beach where she lost her brother. Anybody happen to know this movie? This has really been bothering me for a while now 😩