This week's Democratic primary debate raised several important questions for voters, such as 'how would the US pay for Medicare for All?' and 'what is the best way to ensure energy security without killing the planet?'

But you can thank the Washington Free Beacon, a conservative news website, for raising the most important and relevant question of all: Why was Senator Bernie Sanders’ head so smooth?

It said the Vermont senator looked "suspiciously smooth" during the debate, and included side-by-side photo comparisons to underline their point.

The website noted that he was looking "spry as ever on the stage in Atlanta" adding: "A little too spry, in the opinion of some medically curious observers."

No 'medically curious observers' were cited, however, in support of the clear implication that he'd undergone some sort of cosmetic procedure.

At a time when Congress is conducting an impeachment inquiry into the president for allegedly trying to strong-arm a critical ally into investigating his political opponent, US immigration policies are creating a humanitarian crisis on the Mexican border, and climate change is accelerating, some may despair that this is what some parts of the internet are concerned about.

But conspiracy theories have become increasingly interwoven with American politics of late. Donald Trump has used a debunked Russia-backed conspiracy theory about Ukraine trying to influence the 2016 election - and then blaming it on Russia - to discredit the Mueller report.

However, there's likely an innocent explanation that can close this latest chapter in American political scandal.

As Mashable notes, almost all candidates wear make-up during televised debates. There is also lighting to take into account, as well as the type of lens and angle used to a particular photograph.