Is it Puberty?!

I remember puberty...it came early for me, so I might be a little hyper-vigilant looking for the signs in my kids. I was 8 years old when the changes started, and barely 11 when my first period came. So now that my kids are almost 9 (girl) and 10 (boy), while I'm hoping I've got a year or two, I'm getting suspicious that not only is puberty arriving, it's arriving for both kids at the same time!
I started worrying about my son because he was checking his temperature every night, sometimes during the day, and sure enough, his body temperature was elevated. Normally, his body temperature is around 97 degrees. But his were in the 99's and at first I thought he was sick. Then it just went on and on and I'm going to settle on puberty as the reason, because I'm thinking my only alternative is something serious like cancer! He has also been more tired, having nightmares, and more recently, has not been able to concentrate. He is having trouble focusing on his schoolwork and literally can't bring himself to sit down and get it done. This is very abnormal for him, and for the life of me I can't find a reason for the sudden change.
I can't find much information online about body temperature changing during hormonal activity in puberty, but I've noticed mine change during pregnancy, and now perimenopause. As I type this, it's 70 degrees in my house and I'm sitting here in a short sleeve shirt. Just last year I would be shivering at 70 degrees. I have a hard time doing a lot because I tend to get much hotter than I remember. So I'm thinking, maybe it happens during puberty, as well. I just can't find much documentation on it!
At this point, I'm hoping it's hormones, because that's natural. Illness is not, and if it is an illness I'm hoping it's nothing serious. If you have any experience with this, or if you have noticed the increase in temperature for your child, please comment!