Sleep is a well-known "target" for regulating mania and other mood swings.
Before anti-psychotics were available/widely used, sedatives and limited light exposure were used to decrease mania. At least 12 hours of darkness, often more, per 24 hours.
Blue, your pdoc is targeting sleep correctly.
He is also cautiously using Seroquel, which is the way to use it unless you prove otherwise. He's not just assuming you will need higher doses. You may need higher doses, yet if so, then you both will know this quickly.
I feel he's trying to balance treatment with keeping you as functional as possible, as you do have job responsibilities, etc.
I feel he's looking out for your interests, trying to help you find a balance where you can function optimally.
He could just hammer you with high doses and doing so might create other problems for you.
I think he's likely a very thoughtful pdoc and has your best interests in mind.
Stay in touch with him, giving him feedback so he knows if/when you need further med adjustments.

WC