Rihanna: Can't Sleep in London!

Rihanna shows off a slightly sheer dress on Thursday (August 29) in London, England.

The 24-year-old entertainer exited her hotel to an onslaught of fans waiting to catch a glimpse of their favorite star.

PHOTOS: Check out the latest pics of Rihanna

“It’s 430 am and I’m up like an idiot! Can’t sleep! Whyyyyyyy????!!!” RiRi tweeted the night before. Must be super jetlagged!!!

It was recently announced that Ri will be performing at the 2012 MTV VMAs next month! Demi Lovato and Frank Ocean are also set to perform at the awards show.