One of my BuzzFeed coworkers wrote an OK to Wake clock review, saying it's basically like giving the gift of sleep to parents with young children.
Promising review:"We've had this clock for four years and it's still going strong. You can adjust the amount of time the green light stays on. You MUST wait until the green light comes on to enter the room or it won't work! If your child comes out before it's on, take them back to bed and walk out.We get them used to it (now with child #3 who's 9 months old) by telling them before closing the door at night 'Wait for your green alien to wake up!'It's a good last-minute reminder. The only thing I'd change is that the dimmest light setting is still a bit bright for my light sleepers, so I have to lay a burp rag or something over the back to make it dimmer. I'm considering buying a second so the older kids can have theirs back!" —Lauren
Get it from Amazon for $32.99.