She goes to sleep at 7pm then she's up for anywhere between 1.5-3 hours in the early hours. Generally goes back down around 05:30-6, and then I get her up for the day at 07:30. She has 1 nap at 12pm that is 1.5 hrs. My son had split nights but he was napping 2-3 hours during the day, and as soon as I started capping his naps he started sleeping though. But this doesn't seem to be the problem this time round as I don't think her nap is too long.
Anyone have any ideas? She's fed when she wakes up so she isn't hungry. Bedroom is kept around 19 degrees and she's in a sleeping bag so she's not hot or cold. She's 9 months old, which I know is a bit on the early side for dropping to 1 nap, but she was fighting her morning nap, refusing to go down for her afternoon nap then also not settling well at bed time. She has no problems falling asleep at nap time or bed time now. My son also dropped to 1 nap at 10 months so I think I just have low sleep needs children.
This has been going on 3ish weeks so not sure if that's a bit too long for a phase/sleep regression as it seems to be becoming the routine now.