You need to treat D3 as a hormone with an ideal range. When your blood levels gets too high (typically over 100) you have trouble sleeping and might have restless leg syndrome. When it's in the ideal range (60 - 80) you sleep like a baby.

Dr Gominak has done a bunch of research on D3 levels and sleep. Her RightSleep program will walk you through how to properly supplement into the ideal range. She has a few videos on YouTube with all the background info. This is my current favorite: https://www.youtube.com/watch?v=n1Qm5x7Lxgc

Having said that, most doctors don't have a clue about D3 dosing. You'll have to do some research.

Most people will overshoot in a month or two if they take 10,000 a day, but I know of people that have taken that level for long periods without ever going too high. It's super personalized.