It works in the sense that it is a clock. When a LO wakes up, she has no idea if it is 5am or 8am - just as you wouldn't, unless you look at a clock. The clock simply shows her if it is 'morning' or 'night'. But of course, she won't go back to sleep just from looking at a clock - that only happens if you are 100% consistent enforcing, 'if it is night we stay in bed, if it is morning it is ok to get up.' My kids clock is set for 6.50 on school days. If they wake up at 6.45 they still have to stay quiet in bed until they see the sun on the clock.