Are you experiencing sudden dips during the night or other odd patterns that don’t seem in line with your normal readings?
No worries - it’s most likely that you are lying in a way so that your arm with the sensor gets less or more blood flow, which may cause a sudden drop or rise in glucose levels.
This is consistent with a study on CGMs that found nighttime drops were highly correlated with subjects lying on the sensor.
The sensor reads the glucose concentration in your interstitial fluid (right under the skin), which could vary if the arm is being smooshed under you (yes, that is the technical term).
Steady decreases in blood glucose are also to be expected at night, especially during REM.