C.I.D. - Season 1 Episode 608

A woman living by herself suddenly wakes up to a noise outside. she goes down to check but doesn't find anybody, Shr goes back to her room and tries going back to sleep but just about then a stranger tries to suffocate her with his bare hands. within moments she wakes up to realise it was all a dream but when she checks her face she finds back was covered blood and she calls the CID.What is the mystery behind this dream and the blood on her face