https://msdn.microsoft.com/en-us/library/windows/desktop/ms687032%28v=vs.85%29.aspx :
dwMilliseconds [in]
The time-out interval, in milliseconds. (...)

Windows XP, Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008, and Windows Server 2008 R2: The dwMilliseconds value does include time spent in low-power states. For example, the timeout does keep counting down while the computer is asleep.

Windows 8, Windows Server 2012, Windows 8.1, Windows Server 2012 R2, Windows 10, and Windows Server 2016 Technical Preview: The dwMilliseconds value does not include time spent in low-power states. For example, the timeout does not keep counting down while the computer is asleep.

Oh, les jolis bugs que ça dû introduire, ça...