Resting energy is off when wearing my watch at night

Hi,

ever since the WatchOS 7 update, I've worn my Apple Watch series 5 to sleep quite a few times. When I do so, my resting energy is way off.

Normally, it should be around 2200 calories per day. When I leave my Watch on the charger at night, it's ok. When i wear it at night, it is around 800 to 1000 calories. This depends on the amount of time I sleep and the amount of time the Watch spends charging. When I wear the Watch at night, resting energy is also off during the day. For instance, I've had hours with 33 calories spent, which is way too low: it should be between 80 and 100 calories per hour.

It could be related to the fact that the Watch does not measure heart rate at night: the Watch seems to associate a lack of heart rate measurement while worn with no calories consumed, which seems absurd.

This is very annoying to me, as LoseIt uses the Watch's resting energy to calculate my energy budget. If it thinks I spend 1000 calories just existing, it throws exercise calculations off by a country mile.

Is there a fix? I've already unpaired and paired my Watch three times: I restored from a backup twice, and I have now configured my Watch as a brand new watch.