I’ve noticed you can enable power saving measures so that iPhone and also Apple Watch doesn’t drain much power over night. Especially on the Apple Watch side and also adds convenience of Apple Watch display not glowing bright during night. It’s distracting and serves no purpose. I sleep with the watch and charge it in the morning before I go to work, so not having it drained much over night is certainly useful.
We can achieve this using Automation feature in iOS 15. Older versions had it, but it was not activating tasks properly and was asking you about it which defeats the purpose of automation. You can find it in the Shortcuts app.
For my power saving I’m using “Low Power Mode” and “Theater Mode”. Low Power Mode disables a lot of syncing and other background features/tasks on the iPhone, where Theater Mode turns off sounds and display on Apple Watch. I like Always-On Display on my Apple Watch 5, but I don’t need it during night and it is quite bright as well as a battery drain.
Set the time when Low Power Mode is enabled to something when you usually go so sleep and set it to be disabled either when you wake up or a bit before that. This way it’ll be saving power, but not really affect your morning routine.
Same goes for Theater Mode. Set it to time when you go to sleep and Apple Watch display will automatically turn off during that period. Set the time to disable it when you wake up or a bit before that and that’s pretty much it. You can still invoke the display by touching it and it’ll show the time for a short time before going off again if you wake up in the middle of the night and want to know the time.
Make sure you disable “Ask Before Running” toggle, otherwise it’ll ask and wait for your confirmation which is not desirable. And this is it. Confirm and it’ll perform the actions at selected time.
You can also go beyond that and actually do other things like turning off WiFi (using “Set WiFi”), disable cellular data (using “Set cellular Data”) and even beyond that by switching to 2G or 3G (using “Set Voice & Data”) during that period over night, depending which networks are still available in your region. 2G or 3G use way less power than 4G/LTE, but you’ll still be reachable for emergency calls. Phone being in such passive mode for 6-8 hours every night is pretty significant, both for power usage as well as data usage.
Be aware that using such measures over night means automated tasks like backups and updating won’t be performed. So, keep that in mind if you use iCloud or rely on automatic updating. I do the updating and backups on my own so it’s not an issue.