Problem is you may never notice it in your dream even if you do use lasers (bad idea).

You don't see what is going on in the physical world - that part is shut off. I'm sure people who sleep with their eyes open don't actually see what is going on. But then again... I sometimes see lightning in my dream when a thunderstorm is approaching, but other times I'll sleep right through one, so this method isn't guaranteed to work all the time.

If there was some way to control it, or only have it go off for 10 seconds when you begin REM sleep, it would be great, otherwise I think it would be an annoyance.