Olivia Munn's beauty essentials are ''water, sleep and sunscreen.''

The 36-year-old actress has revealed she has a simplistic daily routine, which sees her rely on three items including a good night's sleep, three litres of water and a sun protecting face cream to ensure she has flawless and radiant looking skin.

Speaking to Byrdie Online about her beauty regime, the 'X-Men: Apocalypse' star said: ''So when you ask what my beauty secrets are, besides Patrick [Ta] and [hairstylist] Christian [Wood], it's water, sleep, and sunscreen.''

And the brunette beauty has revealed she will ''always'' wear make-up even if she is just popping out to do her food shop because she doesn't want to be shocked when she catches a glimpse of her reflection if she goes au naturel.

She explained: ''When I get up in the morning, even if my boyfriend is gone all day long, I still do my hair and make-up. I do it even if I'm just going to the grocery store because I want to do it for me. It makes me feel good. I think, especially for young girls and women, when we start to do things for ourselves and not for anybody else to see it, that's when other people do see it.

''I always feel like whenever I get up and get ready (and that doesn't always mean doing full make-up, sometimes it just means I'm getting up and putting on a little blush), it's worth it just so that if I were to pass by a mirror I would feel good about myself.''

And the American star has revealed she ''loves'' to experiment with a variety of cosmetic products and enjoys wearing ''bright and fun'' coloured make-up, although a touch of concealer, a sweep of mascara and just a little bit of lip balm is her ''go-to'' look.

She said: ''[My beauty look] was probably what I normally do: a little concealer--I like the YSL Touche Éclat --and a little blush. I did my eyebrows, chapstick, and wore my hair down. That's my go-to.

''I love playing with make-up and wearing bright and fun colours, so I kind of do that all the time.''