Windows 10 Windows has Started Shutting Down on Its Own

Beginning last week, Windows 10 has begun to shut itself down randomly. I will be working away on some task or watching a video and boom, the screen goes dark. The power is on but the computer is off. It happened twice Wednesday evening and twice on Friday evening. It has not happened every day but Windows 10 did recently update itself. No blue screen. No error message. It simply shut down suddenly. Any suggestions please? Thanks.

Ken