I let DS go to the slumber party

at my mom's last night with his 2 cousins (7 and 9 years old). He didn't go to sleep until midnight. How he hung with them that long I have no idea b/c he didn't nap yesterday. He got up at 9am this morning and again today Hno nap. Luckily as of now he's in a good mood but it's gonna be an early night for sure! He had a blast! Glad I let him go!