Actress Anna Kendrick fears she makes a fool of herself whenever she takes sleeping aid Ambien on a flight because she always wakes up to a "surprise".

The Pitch Perfect star reveals she relies on the prescription medication to help her get some much-needed rest on long-haul flights, but she can never recall anything that happens after she swallows the pill.

She took Ambien earlier this week (begs15Dec14) while on a flight from London to New York and woke up to discover she had pulled on every item of clothing from her hand luggage - all while in a drug-induced haze.

Describing her most recent experience, she says, "I've got that London flight kinda down to a science because of the Ambien. Thank God for the Ambien! It's a hell of a drug... I just sort of black out the moment that I take it and I wake up to a surprise every time...

"This last time, 'cause you have to be ready to go to sleep (as soon as you board), I took it and I remember thinking, 'I should put on something comfy to sleep in' and then (I remember) nothing. And when I woke up, I was wearing everything that was in my carry on bag, and I had a 90-second video of my salad...

"It's nervewracking because it's like, was it a hurried process? Was it like, I'm sleepy, I'll just put these on? Was it like, I'm giving the other passengers a fashion show? I don't know, I'm not sure that I want to know... (I have) no recollection of this happening..."

And Kendrick admits it's not the only strange thing she's done while on Ambien.

She continues, "(I have) no recollection of putting Dvds in my fridge, or the one time I made enough scrambled eggs to feed a small army... It's just like a time travel and a little surprise... I woke up like, 'Well, that (sleep) was good, what's happened to me? What have I done?'"