If sleep is interrupted during the first phase, or cut short during the last, new information retrieved during the previous day takes longer to recover, or is lost altogether. Parent retrieves pacifier, rocks and soothes baby, provides four more pacifiers for good measure, stumbles back to bed. I'm afraid of monsters. Parent turns bathroom light on, lies down with middle boy until he is calm again, stumbles back to bed. It's still too dark in my room.
Parent turns on hall light, lies down with middle boy, stumbles back to bed.
Parent fills sippy cup with water, hands it to boy, turns dining-room light on for good measure, stumbles back to bed. I wet my bed. Oldest boy grumbles in his bed on the other side of the room, turns over, slams his pillow over his head. Parents stumble back to bed. I can't go back to sleep.