Glow is one of my favorite effects to add to a nail design – it just makes it so much cooler! The glow on these nails designs activate when it absorbs enough UV light. The longer it is exposed to UV, the longer the glow will last (and I mean HOURS). Personally confirmed: I spent a full day out in the sun at Disneyland with glow in the dark nails. Sunset happened at 8pm and my nails were still glowing 5 hours later at 1am.