Rihanna only sleeps for ''three or four hours a night''.

The 29-year-old singer has admitted she finds it tough to switch off from the demands of her day-to-day life at night and, as a result, she gets markedly less sleep each evening than the average person.

She shared: ''I have a lot of trouble switching off. Even when I get home early, which means before 1am, I start binge-watching shows or documentaries, which I love.

''I can't go straight to bed. As a matter of fact, I only sleep three or four hours a night.''

The 'Diamonds' singer regards the likes of Whitney Houston, Mariah Carey and Tina Turner to be among the biggest inspirations in her own life.

But perhaps surprisingly, Rihanna has also taken inspiration from the late Princess Diana - and in particular, the so-called revenge dress she wore to the Serpentine Gallery's summer party in 1994, shortly after it emerged Prince Charles had been unfaithful to her.

The fashion-conscious star told French Vogue magazine: ''Every time a man cheats on you or treats you badly, you need a revenge dress. Every woman knows that.

''But whether her choice of this knockdown dress was conscious or not, I am touched by the idea that even Princess Diana could suffer like any ordinary woman. This Diana Bad B***h moment blew me away.''

Meanwhile, Rihanna previously admitted that her fashion sense was hugely influenced by her male friends.

The 'Work' hitmaker recalled: ''When I was 13 or 14, I didn't want to wear what my mom wanted me to wear. I was very much a boy in my style, my demeanour.

''All my friends were guys. I loved things that boys did. I loved being easy with my clothes. I loved wearing hats and scarves and snapbacks on my head. It was my way of rebelling. I wanted to dress like my brother.

''After a while, it was just easier for Mom to dress us both the same. We wore the same jeans, the same T-shirts.''