Define the symptom
Decide what you are seeing: a full wake with the display and login screen, a brief dark wake that you only notice through warmth or battery use, or a Mac that never entered sleep because an app held it awake. Note the time you put it to sleep, when you noticed it awake, the battery change, and connected devices.
Activity Monitor's Energy pane includes a Preventing Sleep column. Check it while the Mac is awake before testing sleep. A process shown there is worth investigating, but a clean list does not rule out a later wake caused by hardware, software, or a scheduled activity.
Reduce variables around the next sleep
For one test, remove nonessential USB hubs, drives, input devices, and external displays. Keep the Mac in the same location and use the same lid state. Then compare that result with the baseline. If the pattern disappears, add accessories back one at a time across later tests rather than assuming the first removed item was responsible.
Also look at settings that deliberately allow wake behavior or scheduled startup. A schedule is an intended event, not a fault. If you change a schedule or related setting, write down the previous state so you can restore it and compare a fresh sleep session.
Read log evidence carefully
Open Terminal and run the read-only command below. Find Sleep, Wake and DarkWake entries around the time you recorded; compare their timestamps rather than treating every log line as a separate full wake. WattGuard presents these records alongside charge changes and reported wake reasons. A wake reason describes a system observation and guides the next test; it is not a complete causal explanation.
Use the same sequence for every hypothesis: establish several comparable sessions, make one reversible change, and recheck. WattGuard's own baseline uses the median of three to fourteen prior sessions. This is more reliable than making several settings changes at once, because an apparent improvement may simply be an unusually quiet night.
pmset -g logWhen to seek further help
If the Mac wakes repeatedly with no clear environmental pattern, update macOS when an update is available and use Apple Diagnostics or Apple Support for hardware concerns. Include your recorded timings, accessories, and controlled test results. That is more actionable than a general report that the battery was lower by morning.