Revising in the dark can cause eye strain. I'd say it's better to revise with bright light because a dark place can make one feel sleepy, or at least make your brain think it's nighttime therefore it's time to sleep which could affect your concentration.
Some people like revising in the dark or with dim light because it makes them feel cosy or they just like the aesthetic. To each their own. I wouldn't recommend it though.
Hope revision goes well.