Mac OS Sonoma Waking from sleep every hour with CSPNEvaluation in logs

I’ve had an issue since upgrading to Sonoma on my 2019 Intel iMac. I have power nap disabled, as every time the computer wakes under power nap, my external drives spin up. My office at home is in the next room to our bedroom, so I hear the drives spinning up & down all night. It has been driving me mad. I’m not a big fan of the new energy saver settings in Sonoma, or the entire settings layout for that matter. When looking in logs using the following in terminal:-

pmset -g log | grep ' wake'

I could see a lot of references to CSPNEvaluation with an hourly wake event. After looking around online I found a solution to this. In Sonoma, even with powernap disabled, the Mac seems to wake on a regular basis by design. If you want to override this function & stop your Mac waking, I recommend the following.

1.  In terminal, type the following command to create an override folder
   sudo mkdir -p /Library/Preferences/FeatureFlags/Domain/
2. Change directory into the folder with cd /Library/Preferences/FeatureFlags/Domain/
3. Create the following file & open the terminal editor with
   sudo nano powerd.plist
4. You will now be in the nano editor, where you need to paste the following code block to override (the folder & file you create as part of this can be deleted at any time if you want to undo it)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CoreSmartPowerNap</key>
    <dict>
        <key>Enabled</key>
        <false/>
    </dict>
</dict>
</plist>

Save the file in nano & reboot your machine. The CSPNEvaluation issue should have resolved & your mac should stay asleep. I’ve just tested mine & it successfully stayed asleep for 10 hours.