Windows

To check why computer was woken from suspend:

powercfg /lastwake

To disable Windows Update waking up the computer, run as Administrator:

gpedit.msc

Then go to:

Computer Configuration / Administrative Templates / Windows Components / Windows Update

Double click on:

Enabling Windows Update Power Management to automatically wake up the system to install scheduled updates

and set it to "Disabled". For swedish Windows:

Datorkonfiguration / Administrativa mallar / Windows-komponenter / Windows Update

Ändra:

Aktivera automatisk väckning via Energisparfunktioner för installation av schemalagda uppdateringar

till "Inaktiverad".