Not meaning to answer for jedberg, however, melatonin production declines naturally with age. The truth of the matter is that sleep hygiene (especially management of light) is probably a lot more important for him than his children. Another important factor is also getting bright light early, which is often neglected and may have relevance for depression and more.

Also, not widely known, melatonin is one of the reasons late night eating can be a bad thing: emerging evidence suggests that receptors in pancreatic beta islet cells suppress the production of insulin in response to the release of melatonin.

Here's a great podcast with Dr. Satchin Panda, a circadian biologist from the Salk who was involved in some of the early research elucidating the effects of melanopsin, which is the photopigment that actually synchronizes our internal clock to light. He drops some pretty amazing circadian knowledge...

https://www.foundmyfitness.com/episodes/satchin-panda

Mostly because of what dpatrick86 said.

They don't have any trouble sleeping nor being awake when they need to. Also, they are only 3 and almost 1, so they just sleep when they want.

Also, my wife doesn't like the yellow lights, so mostly I can only "shut down" the house after she goes to bed or at least retires to the room for the night.

As the kids get older I'll probably start teaching them about good sleep hygiene if they seem to be tired all the time.