Although Metaphysical Megan claims the pubic practice promotes better sleep, regulates the circadian rhythm and increases energy, others are not so convinced.

One adversary to ass-sunning is actor and Academy Award nominee, Josh Brolin.

The No Country for Old Men star took to Instagram on Saturday to share a strongly-worded message regarding the "ancient Taoist" technique.

"Tried this perineum sunning that I've been hearing about and my suggestion is do not do it as long as I did," Brolin wrote.