I have a work assigned HP Elitebook. Worst laptop I've ever had to use.

Here are some highlights, though I know probably some are from the insane bloatware/crapware/"security" software and Windows group policies IT setup:

- If I leave it with the lid open, and come back to it several hours later, it's fairly cool, but:

- If I leave it with the lid closed, and come back to it several hours later, it's blowing it's fans at maximum speed and the entire thing is uncomfortably hot

There are multiple causes/symptoms:

- Poor thermal design, causing the heat to build up faster than it can vent it even at maximum fan speed (several of the vents blow directly at the bottom of the screen, so when the lid is closed that air has no where to go)

- Occasionally simply closing the lid even when its been cool has caused the fans to hit maximum speed immediately even if its still cool

- Poor firmware controlling the whole cooling system

- Poor IT mandated software running amuck in the background

That last point is one of the worst parts when combined with the "air vents are blocked when the lid is closed" design.

At seemingly random times during the night, with the closed laptop, and even if the laptop was in standby or hibernate OR shut down fully, it's managed to turn itself back on, start up the IT bloatware, causing very high CPU usage and thus once again maximum speed fans.

I'll say that again to emphasise it. Even when fully turned off, it can turn back on. This is actually pretty scary and dangerous, because it's totally unpredictable. I cannot leave it in my laptop bag overnight, for example, in case it decides to turn on and start cooking itself.

I have on several occasions purposely let the battery drain just to stop it being able to turn on by itself.

It has on multiple occasions woken me up in the middle of the night from the fan noise too.

/rant

Sounds like Windows is doing its updates. It knows whether lid is closed. It likes to do that in the middle of the night, yes, sometimes even playing a notification sound. Hopefully you don't leave volume at max.