More than 8 hours and 30 minutes of sleep are counted toward Pokemon that need sleep for evolving.

[lament mesa]

I decided to test out if more than the maximum amount of hours you're able to record a day would count toward pokemon that require a number of sleep hours to evolve (riolu, eevee, etc.) Thankfully, you are able to. This means you could potentially leave your phone to track your sleep if you aren't too serious about the game tracking your sleep.

[charred briar]

if you feed snorlax dinner at 6pm and put the phone to sleep you can do 6pm-11:30am and not miss a meal you can give breakfast just before lunch starts

17 hours towards a pokemon. granted you dont have anything in between like work

could be a strat for a day off