Lady Gaga burst into tears Wednesday because she could not believe how successful she has been.

The 28-year-old singer took to Twitter to pour her heart out and admit she is feeling "overwhelmed" by what she has achieved in her career and thanked her fans, who she calls 'little monsters', for their ongoing support.

She tweeted: "Spent a lot of time crying today, happy tears, but many. I can't believe my life. Being able to buy nice things, travel, it's overwhelming. Some days it hits me so hard, reality, I can't express my gratitude enough to monsters+team for believing in me. U changed my families life. (sic)"

The Born This Way hitmaker admitted she is feeling "very humbled" at the moment and has vowed to continue to keep paying her supporters back by producing plenty of music and performing gigs.

She wrote: "I hope with my music, shows, and message I can share with you all these blessings though the beauty of art. Love, a very humbled Lady. (sic)"

While Gaga paid tribute to her loyal fans, it has emerged that nearly a third of people think the singer - whose real name is Stefani Germanotta - is the most likely celebrity to be an alien.

In a survey commissioned by TV channel Syfy, to mark the start of 'Defiance' season two, 31 per cent of people ranked her above the likes of Tom Cruise (16 per cent) and Boris Johnson (12 per cent) as the most likely star to be an extra-terrestrial.

Bizarrely, this comes shortly after it was reported that Gaga wants to play a gig in space with David Bowie after she was booked to perform on a commercial Virgin Galactic voyage next year.