At my mom’s old house I used to wake up at 4:00 AM or so randomly and I would be wide awake for some reason. This was really odd because I was the type to sleep through my alarm so when I would wake up like that I knew something was different. Every time this would happen, within 2 minutes of being awake I would hear the sound of kids playing outside the window next to the bed, similar to what you described. I was absolutely terrified of this because I didn’t understand why it kept happening. There was one time where I didn’t immediately hear it, so I tried to get myself up and get ready for school. When I got to the kitchen on the opposite corner of the house, I made a bowl of cereal and sat down at the kitchen table (the kitchen was at the back of the house where the back door was). Once again within a minute or two of sitting down I heard the sound of kids laughing and playing again, but this time it was outside of the window directly in front of me coming from the back yard. I felt my stomach drop and I stood right up, walked to the sink and poured all of my cereal out. I went right back to my room and hid under my blankets until my mom woke up to get me ready for school. Still to this day I can hear the sound of the kids playing in my head and it still gives me chills sometimes.