A perfectly wonderful internal clock exists in all humans.
For babies and toddlers this tool can be a saving-grace. When utilized correctly it makes naps and bedtime much smoother.
When misunderstood it can cause chaos and a child who is over-tired...which masks behind a hyperactive state!
The best way to make sure your child is staying on their ideal schedule is to follow their appropriate awake time windows. As a child grows this window becomes longer and longer until they're able to stay awake all day without a nap. If your toddler has an appropriate bed time then by the age of 3 they no longer need a nap. Between birth and three years you must navigate the awake time waters very carefully.
Breathe easy though...I have provided a helpful Ideal Awake Time Guide that you may use as your child grows. If you stick with your child's appropriate time window, you'll find that nap and bed times become much smoother.
Your Pediatric Sleep Consultant