You'd be better off puchasing a magnetic cover that fits the Glo to take advantage of the auto-sleep and wake by just opening/closing the cover. You have full access to the light switch then (although I always leave my light on, it just makes the page background appear whiter when I don't need it and it's not a battery drain).
This is the cover I have, only $5.99, and I love it.
Here it is in different colors in case blue isn't your thing.
The only problem some have with this cover is when you flip the cover back, sometimes the magnet is strong enough to turn the reader off again. That's easily solved by putting a little bit a thickness inside the cover under the reader of aluminum foil or even paper towels. I had to do that and it works perfectly.