I know most people don't have this issue but I thought I'd post it here because I've come across it a few times now in Windows 10 and it can take a while to find an answer if you're not aware (anyone searching google hopefully). I've come across a few PC's (Desktops and Laptops) where the CPU usage was pegged at maxing out one core and also Disk usage was constantly writing to the SSD (not good) or hard drive. After looking into resource monitor, you can see it's the "System" and "System Interrupts" that's causing it, writing loads of information to a log file called SleepStudy/UserNotPresentSession.etl on the C drive (huge clue there!). Turns out that if certain PC's or laptops (perhaps hardware specific) don't wake up properly or there is a powercut when it was sleeping, next time you boot the system keeps logging all the system devices that would be using power in sleep mode. Problem is, the computer is no longer sleeping so that would be a huge amount of devices and interrupts it starts to log! Sleep study continues when the user IS present and in a fully powered up state - hence the huge logging and system interrupts being hammered. My brother complained of a slow dual I3 series 4 desktop PC, it has literally written GBs of data to the SSD and been maxing out one core and hammering the interrupts process until I put it to sleep and woke it up again then everything was fine (shutdown/reboot didn't stop the logging) Just a heads up as it seems this sleep study has a few bugs still in Windows 10.