Tip: The value in temperature tracking is variance to baseline. Body temperature in isolation is not of great use as we all have different baselines. Monitoring changes over time gives useful insights.
Setting Up Wrist Temperature
You need an Apple Watch Series 8 or Apple Watch Ultra, then follow these 3 steps:
(1) Turn on Wrist Temperature in AutoSleep Settings
Open the AutoSleep Settings tab
Scroll down and tap into Wrist Temperature
Turn on the 'Show Wrist Temperature' switch. Accept any health permissions that may show for wrist temperature. This will now show as a new tile on the Today tab
The default is set to degrees celsius (c), but you can change to fahrenheit (f)
(2) Track Sleep with Apple Watch
Open the Watch app on your iPhone (it looks like a black icon of a Watch). Scroll down and tap on 'Sleep'. Make sure that 'Track Sleep with Apple Watch' is turned on (see below):
(3) Turn on Sleep Focus
At bedtime, you need to ensure your Watch is in Sleep Focus mode to capture temperature data. Apple quotes this needs to be on for at least 4 hours to capture temperature. Swipe up on your Watch face to open the Control Centre, tap on the half moon icon to open the Focus/Do Not Disturb options. Tap on Sleep to enable the Sleep Focus mode, the half moon icon will change to a bed icon. This will turn off the Watch display and put it into a Do Not Disturb mode (see below).
Wrist Temperature Details
Tapping the tile from the Today tab will take you to the Wrist Temperature Details page, which includes a Temperature and Baseline. A simple gauge display and needle shows where your wrist temperature is currently at. Ideally you are trying to be in the middle green, as this is a (+)( - ) 0.25 degrees window compared to your 7 day baseline. The outer green shades are (+)( - ) 0.25 to 1.00. The orange is (+)( - ) 1.00 to (+)( - ) 2.00. The red is greater than (+)( - ) 2.00. If you have changed the unit from Celsius to Fahrenheit in Settings, the same range will be converted to Fahrenheit and applied.
Tap any value to drill into the Trends view, with summaries on baseline changes and 7 day averages. Tap any part of the graph to view the pop-up details for that day:
Seeing a Failed Message after activating Wrist Temperature?
When you set up the AutoSleep app you indicated that you want to support older Watches by turning on this switch in AutoSleep Settings. This disables noise and other features found on newer Watches. You may have upgraded Watches in this time but left this switch on unknowingly. Here is how to fix it:
Go into the AutoSleep Settings tab
Go into Advanced Options
Turn off the support older Watches switch
Go back to Clock tab
Exit the app
Force close the app (swiping up, or reboot the iPhone if you do not know how to force close)
Go back into the AutoSleep app
Pull down to refresh and it should now ask you for any new permissions. Accept permissions and you should be fine.