My 3.5 month old is in the beginning of his 4 month sleep regression�?aka waking at 30 or 40 min naps and went from sleeping 8-10 hours overnight to waking every 2-3 hours! With this Kaiya Baby sleep sack, he is sleeping so much better. Still a few shorter naps and waking occasionally some nights (I don’t think there’s a magic single fix- I’m not claiming that!) but this makes him feel like mama is snuggling him during naps and at night, so over half of our naps are now 1.5 hours again and most nights we just need to get up once for a hand on the chest to comfort back to sleep! Baby is in a 6-18 months, 2.5 TOG, but also in 6-9 month clothing for reference :)