What happened to the sound profiles that were in Lollipop? I recently bought a new phone to replace my old one. The old phone is running 5.1 (Lollipop) and has "Predefined [sound and notification] profiles" (see screenshot). However, there seems to be no equivalent in 8.0.0 (Oreo), and as a result this new phone has been sitting on my desk all but unused for almost a month now.

Searching around it would seem I have to install some overly convoluted app with features I don't need (or want) to achieve the same result, but that can't be right, can it?

I don't think I need to explain what I want to accomplish, but in case I do and in case my twice-daily routine triggers someone to suggest an even better solution: I have one email account (of four set up in a third-party mail app) that I need to alert me 24/7. Nothing else needs my attention 24/7. So every time I go to bed I turn off notifications for the other three email accounts, turn off notifications for the phone, turn off notifications for text messages, turn off notifications for BBM, turn off notifications for a VoIP app and set my sound profile to "sleep". The sleep profile has all sounds and vibrations turned off so that, other than the very occasional sufficiently important incoming email, my using the phone won't disturb my wife. In the morning I reverse all of that.

I'd be happy with just having the sound profiles back -- the twice-daily routine is a bit tedious and ridiculous, it seems to me, but it's not that onerous -- so that's the main thrust of this question. Thanks.

Screenshot of "Sound &amp; notification" profiles in Lollipop:
What happened to the sound profiles that were in Lollipop?
  Unless I am mistaken, they have been removed on Android 8.
  
  The sleep profile has all sounds and vibrations turned off so that, other than the very occasional sufficiently important incoming email, my using the phone won't disturb my wife. In the morning I reverse all of that.


You can a rule (actually 2) to achieve what you describe:

Goto Settings -> Sounds -> Do Not Disturb preferences.


The first rule will be a Time rule. Add a new Time rule or you can modify the existing Weeknight rule. You select the time, date when it should apply, set the preference to Total silence. 
The second rule will be an Event rule. Add a new Event rule or you modify the existing Event rule (you can change its name). In "During Event for", select the email address it should apply to. In "Where reply is", select "Yes, Maybe or Not replied" date when it should apply, set the preference to Total silence. 



  Searching around it would seem I have to install some overly convoluted app with features I don't need (or want) to achieve the same result, but that can't be right, can it?


It is right, to have the sound profiles or something that looks like it, you will have to install a 3rd party app. I can try Sound Profiles (+ volume scheduler). Give it the appropriate permissions and you can use it to manage sound profiles again.

Disclaimer: I am not related to the app developer(s).