My friend has one of these shelf-light-bookmark combos, and I have to say: I’m not a fan. In theory, they’re sleek, fun, and save space in one’s bedroom. But the very thing that makes them compact (the sensor that turns the light on upon removal of the bookmarked book) also makes them impractical. Closed books on the main shelf, when taken down, can’t activate the light in the same way that an open book on the other shelf can — so there’s a lot of shifting around (in the dark) if one samples multiple books in one night.