I've done a few nap shows here and there and agree with what
@THE MOLLIE MARIE and
@MarieElise said. It's not a big earner (pretty sure that's across the board and not just me) but it can be a nice little top up when you need the money but don't have the energy for your typical shows. Especially during competition weeks, I've had days where I earnt more per hour in my sleep than during a normal "trying to be friendly and bubbly and interesting" cam shift.
Definitely the hours are the main appeal and are the reason I started doing them - I just didn't have enough time in the week to meet competition minimum hours but didn't wanna miss out on the bonus pay for being in the top XX earners. I've not done one in ages because I'm too busy to even attempt to take part in the competitions recently, but I did find that doing them every now and again brought in more interest than I was expecting it to. I think a lot of people see it as a fun little novelty thing. I doubt if I did them more often that I'd continue to see the same results.
Also, I made the best money when I was just chilling, pretending to sleep and "woke up" for 5G or more tips, sleepily interacted with the people in the room until the tipping died down again then "went back to sleep". When I was genuinely fast asleep and either the buzzes <20G weren't strong enough to wake me up, or I'd accidentally cut the signal off from my lush so didn't get woken up (only saw the tips at like 3 or 4am on my earnings sheet the next day), I was much less successful. You could see people would try with different sized tips but if they weren't getting at least a bit of a moan or something to acknowledge their tips, they'd give up and move on.
I really don't know how significant "ranking" or "placement" on SM is to your overall success on the site but in theory if it doesn't matter at all, I'd say sleep shows are 100% worth doing because even 25G in a whole night is still money for virtually nothing, so nothing to lose! But that's only if placement doesn't matter and I'm not sure I'd wanna risk finding out the hard way.