good for you John keep it up even if lighter reps is better than nothing. Am sure it will help you sleep and get stronger and hopefully prevent further weakening of the body as what normally happens as we age. I visited my kid who lifts HEAVY weights all the time in his gym and he was doing like 8 sets of 350lb. squats and every single time his knees and/or ankles were POPPING/CRACKING going back UP. He says that is normal but to me is not he is only age 20 now and wonder what will happen as he ages keeping up those enormous weights in special tight equipped suits. I tried just picking up on my neck the 350lb. squat bar had NO intentions of going down would NEVER get back up no way and that was enough for me. back in the day 400lbs. was about my max where as my kid is near doing 600lbs. about same 200lb. weight at same age. He sees his heavier/bigger lifting buds do more so thinks he should be able to match them. One guy is a TANK competes in worlds strongest man events or did in his prime big dude 375lbs. or so can do 800lb squat/deadlifts and over 500lb. bench presses. He makes me look like a twig...

From age 20 to 27 I did heavy barbell work and routinely squatted for reps at well over 300 lbs, after a time my knees hurt way more than I knew was healthy.
At 27 I started practicing karate and my knees healed up shortly after that, ever since then they've been fine. I see power lifters that can't move and feel bad for them. A good friend of mine was a PL for many years and has since switched to kettlebells and running, says he feels better than he has his whole life. Another guy I know is in his 70's and beat to hell, surgeries.. replacements.. you name it and he's had it done. He's still in the gym chasing poundages because that's what makes him happy.
I have my share of past injuries that hold me back to a degree, the worst of which is a rotator cuff tear from throwing a baseball 7 yrs ago at my son's baseball practice. Mace work and kettlebells have it back as strong as it's gonna get, so I'm happy.
I hope your son finds his path, whatever it is, and that it's a healthy one for him.