Okay I'm on the Retin a and HQ regime. And I use Hydroquinone twice a day.. but the thing is.. I have messed up sleeping patterns so I use it at different times every night & day.

My question is.. how many hours after using at at night (or day) should I use it again? I'm always thinking 12 hours... since that's half a day.. but not sure.

What do you suggest?