Apple Watch Ultra on the inside of wrist while sleeping?

I wear my Ultra basically 24/7 and I love it’s sleep tracking functionality. However, since I sleep on my back mostly with my arms raised above my head, the Watch presses into my wrist and I often wake up with a mild numb sensation. As a result I have to loosen the Watch considerably, at which point I might be losing a lot of accuracy anyway.

Alternatively can I wear the Watch on the inside of my wrist exclusively while I go to sleep and still retain the data accuracy to some vague extent? If not, is it okay to loosen it in the regular position or do I just have to bite the bullet and wear it like I normally would during the day?