How to make an Android smartphone actually go to sleep? When I turn the screen off on an Android smartphone, I want battery life to be conserved.  Thus, I don't want any third-party apps running in the background, and I don't want the device periodically turning on WiFi (or connecting via 2G/3G/4G/5G).

I set up a test Android Samsung smartphone running Android Nougat, and installed just 25 popular apps.  I set all 25 apps to "Always Sleeping" in Settings.  I then let the device sit for 8 hours with the screen turned off.  During those 8 hours, the Android device connected to a WiFi router 59 times and transmitted/received data each time.

I don't want to turn on Airplane Mode, because I still want the device to be able to receive and log incoming phone calls.

Is there a way to accomplish this with Android (on a non-rooted device)?
As discussed in comments

You want to make sure that the device enters doze mode quickly and disconnect wifi / mobile data when the screen is off. Aeroplane mode is not an option because you need to be able to make /receive calls.

You can achieve that by Naptime app:




Naptime lowers your device's power consumption while the display is off by empowering Android's built-in doze power saving functionality.

Faster idle means less power being consumed uneccessarily. By default doze can take a while to kick in so Naptime just speeds-up that process automagically for you.

It can also automatically disable W-iFi, mobile data, location &amp; bluetooth as soon as doze kicks in.



In addition, Naptime  can also help in enabling doze while in motion (phone in your pocket and you are walking).
It requires root but for unrooted devices it works with elevated privileges through adb commands given in app instructions.
This is a one time process and need not be applied on reboot (AFAIR).

In addition, have a look at this question How to tame &quot;Phone Idle&quot; battery drain on unrooted device? for other apps that can help you. I would recommend you try Wakelock Detector [LITE] (XDA thread)  which is handy in detecting apps that keep your device awake. It gives a better metric than the one you mentioned in question (make sure you follow the instructions).

You can identify such apps and decide on suitable alternatives.

As a second line of defense, in case you aren't happy with Naptime, try, Greenify is another useful app that can come in handy to tame troublesome apps. This works with unrooted devices with adb privileged permissions. Alternatively, you have an open source app Brevent that works as well but adb privileged permissions are required after a reboot. IMHO, with improved Android battery management in recent versions, you may not need this line of defense at all.

Also see this for more Disable autostart on boot and restrict background execution