My children don't sleep much, never did even from babies. They are never physically exhausted. They do three hours of hard slog at gymnastics or a full day at taekwondo competitions and they look and act as fresh as daisies! It's crazy!
Here are the things that worked for me I banned naps at Kindy/ school. I told the teachers that if they let my kids sleep I will ring them on their personal phones at whatever time my kids actually fell asleep at night to let them know how much it affected my life
I could tell exactly how long my kids were left sleeping at kindy because they would go down exactly that number of hours later!
I put them to bed at 8:00 every night even if they were not tired ( I have since moved this to 7:00 because they are up at 5 am) sometimes they are not ready to sleep so they read for up to an hour. Then I turn out the lights. I figure quiet time in their rooms is resting for their bodies even if it isn't sleep.
As they have gotten older and their physical activities are much more demanding they sleep better. They sleep longer and deeper. They still don't sleep as much as most kids their age.
Someone told me when my children were babies that smart kids don't sleep. It seemed to fit with all I knew my kids were doing ( their brains just didn't stop!) so I think that thought kept me sane
I also played alpha and theta music in their rooms as young children. It's relaxation music. It drops the brain waves into a lower pattern like sleep. It's relaxing if nothing else
I would take a sleep diary for 2 weeks and add up the total sleeping hours. Then compare them to the average and decide if you need to see a doctor. You may be surprised at the total hours once you add in naps.