What does your nap schedule look like? My son typically can be awake for 90 minutes to 2 hours and then gets tired. Recently he has been taking really short naps, but he does go to bed pretty early 5:45-7pm, usually the earlier part of that. And sleeps really well through the night. (Wakes around 2-4am to sleep then goes back to sleep until 6/7am)
Re: 5 month old naps
I wake him up from his morning nap after 30 min or 1 hour (he gets to sleep longer if he has an early wake up that morning). His afternoon nap is typically from 1:30-3:30 and I sometimes have to wake him up from that and his evening nap ends no later than 6 pm no matter when he falls asleep. It usually ends up being 30 minutes. His overnight sleep is usually from 8:30-8 am and his wake window is 2 hour-2.5 hours.
But he also doesn't sleep at night. Lucky you! We somehow hit a second regression over here and are up every hour or two and have regressed in falling asleep on his own too. So frustrating!