To have a nightmare.
Any bad, miserable, difficult or terrifying situation or experience that arouses anxiety, terror, agony or great displeasure.
A very bad or frightening dream.
A feeling of extreme anxiety or suffocation experienced during sleep; Sleep paralysis.
To undergo or witness something unexpected.
To attack unexpectedly.
To take unawares.
To do something to (a person) that they are not expecting, as a surprise.
To cause (someone) to feel unusually alarmed or delighted by something unexpected.
To cause surprise.
The feeling that something unexpected has happened.
Something unexpected.