Why won’t my baby nap in the cot after CIO success at night?

We just sleep trained our 5.5-month-old daughter using CIO, and it has really improved our nights (separate post on this incoming!) — we went from 7–9 wakeups with crying to just 1–2. But none of those new sleep skills have transferred to naps. 😩

Before sleep training, we were babywearing or contact napping, with only the occasional cot nap. Now that she’s sleep trained, we’ve been trying to do all naps in the cot — but she cries a lot (like, screaming crying for 15+ minutes). Before, when we were wearing her, she’d fuss or cry maybe 8–10 minutes, but this feels so much harder.

We’ve been trying to follow the “Nap training — a gentle method” post by u/Comprehensive_Bill, but we often end up giving up because the crying feels too intense.

Our current wake windows: roughly 1.5–2 / 2 / 2.25 / 2.5 (depending on her sleepy cues). The day rarely goes as planned though, because long crying stretches delay or cancel naps. She falls asleep easily at bedtime (~7pm), even if her last nap ends around 5:15.

We’re still on a four-nap schedule since her naps are only 29–31 minutes. We’re open to shifting things around if that might help.

Usually, she’ll fall asleep right around the 15-minute crying mark, but lately she’s been sobbing so hard at that point that we’ve ended up rescuing the nap — either with a pram walk or nursing to sleep. Her pre-nap routine is: sleep suit → dark room → sound machine → sing Baa Baa Black Sheep twice.

She currently has a bit of a runny nose — could that be why she’s fighting naps so much?

What can we do to help her nap in the cot without so much crying? Could she be a “power-down” baby? And if she’s sobbing intensely for the full 15 minutes, does that suggest she’s under-tired or overtired?

Thanks so much for any advice 💛