Hello Emotionalities.
Welcome to Apple Support Communities. We understand that you don’t wear your Apple Watch to bed, but your heart rate is being recorded during that time. We’re happy to help.
We’d like to have you do some basic troubleshooting to see if the Apple Watch records your heart rate when not wearing it. This will allow us to isolate the cause.
Please use the steps here to restart your Apple Watch: How to restart your Apple Watch - Apple Support
Please use the steps here to restart your iPhone: Restart your iPhone - Apple Support
After restarting both the iPhone and Apple Watch, does the Apple Watch record your rate when you’re not wearing it?
We’d also like you to update your iPhone to the latest iOS version using the steps here: Update your iPhone, iPad, or iPod touch - Apple Support
Update your Apple Watch to the latest watchOS version here: Update your Apple Watch - Apple Support
We look forward to the results.
Take care.