Same here I use Peaks for the same purpose of using sleep data to calculate my energy levels and circadian rhythms, these are useful for appropriately predicting optimal times to get sunlight, when to stop eating dinner and other activities like working out ideal times; etc.I've been wearing mine for a couple of years now. I don't really need to but I have an app called Athlytic that helps track my training (running and cycling) and recovery and it uses sleep data (amongst other things) to give me an estimate on my overall level of fatigue and stress, which I can use to train smarter and minimize overexerting myself.
I find the braided solo loop is by far the most comfortable strap to wear, especially while sleeping. It breathes well and there is no metal clasp or pin that can be uncomfortable.
Any band including leather bands I give it the go ahead for sleep tracking. The only bands I do not sleep track with are the link bracelets as they are heavy and uncomfortable to wear.