Identify the operating state
Record whether the MacBook was connected to power, whether an external display was active, and whether a keyboard or mouse was attached. Apple documents using a notebook with an external display as a specific configuration. A closed lid does not automatically mean the Mac spent the entire period in ordinary battery-powered sleep.
If the display remains active or the Mac is warm, first determine whether that behavior is expected for the setup. Do not interpret a desktop-style configuration as an unexplained sleep event.
Compare a minimal setup
For one controlled test, disconnect nonessential hubs, storage, adapters, and displays, then use the same sleep duration and location as usual. Compare the resulting charge change and wake history with a normal session. Reconnect one item at a time only after recording a meaningful difference.
Activity Monitor can show whether an app is preventing sleep before the test. It cannot provide a complete explanation for later activity, so use it alongside the configured display state and the sleep timeline.
Use WattGuard as an investigator
WattGuard can summarize macOS sleep, normal wake, and dark-wake history with charge changes. This helps show whether the interval included a genuine sleep session, but it does not control an external display or promise that a closed lid produces a particular state. A wake reason is a lead for the next test, not a final cause.
If you need the Mac to remain awake with an external display, choose a tool or macOS configuration designed for keeping it awake. If you need ordinary sleep, remove the display setup from the test before changing unrelated power settings.