Pop star Madonna has purchased oxygen machines for each one of her homes, to help her boost her energy levels and combat jet-lag.

The HUNG UP singer originally bought the machines to give herself oxygen facials, which help her maintain a porcelain doll-like complexion.

After indulging in the facials for over a year, she discovered other uses for the machine.

She explains, "You can also take the oxygen machine and inhale if you're feeling really tired or jet-lagged, which is one of the reasons I have them at home.

"You just lie down for 10 minutes and put it in your nose. They are really great."