My 4 month DS has been waking at around 9/9.30pm each night for the last couple of weeks. His bedtime is around 6.30pm and he wakes at different times each night. I give him a BF then he sleeps until around 2.30am and will sleep again until 7am. It's really weird cause he used to sleep until around 12.30/1am for a few weeks then something changed and I can't figure out what. I thought he might be too hot so I've tried to keep him cooler in the first part of the night. I though maybe it was because he was going to sleep when it is bright then waking when it is dark so tried a night light, but I think that made it worse cause he then woke more throughout the night. He's really not happy when he wakes and isn't getting a good block of sleep because of it. Anyone had this happen???