Deep sleeping apps means they will never run in the background. They will only run when you've opened them. I have a few apps in sleeping, which still alert me notifications and I still manage to update them. I'm guessing the deep sleep apps you won't get any notifications. So don't put any of your most used apps to deep sleeping. Especially your messaging apps and emails.
Here is what I recommend and personally use: Sleeping: • Gmail • Google Play Store • Google Home • Google Maps • Samsung Quickstar • Samsung Voice Recorder • Whatsapp • Youtube • Calender Deep Sleeping: • Camera • Calculator • Ebay • Instagram • Gallery • Galaxy Themes • My Files • Link Sharing • Paypal • Good Lock • Samsung Internet • Samsung Notes • Sound Assistant • Video • Three App • Dictionary • Files • Nationwide • Seperated Apps