my 4 month old baby has started having epic naps

[hmmmum]

she sleeps 10-11 hours at night (wakes once for a feed), now for last few days she's been having massive naps in the day. Yesterday afternoon she napped for two and a half hours and I woke her to make sure she'd sleep at night. Done the same today - she is in very deep sleep right now. She never used to nap for this long.
anyone else experienced this sudden sleepiness at 4 months? could it be to do with teething / a growth spurt?
thanks

I have a 15 week old.

Perfectly norma for usl. My dd2 while not sleeping through (still wakes for a feed but straight back down) can easily have a 3 hour nap in the day or a couple of 2 hour naps. DD1 was the same.

It could be that she is tiring herself out more now with all the new experiences, or a growth spurt - they are usually about 16/17 weeks I think because often that is why people consider weaning.

I wouldn't worry but then we are a sleepy family generally. Just enjoy the silence!