It's 4 a.m. Why aren't you mapping the human genome? Or devising an innovative new way to clean our oceans? Or at least curing the common cold?

Well, in the words of JK Rowling, who knows a thing or two about witching hours, "Piss off."

It seems a lot of people are in resounding agreement with the author, who tweeted her disdain for that not-so-magical hour earlier this week — and found nearly half a million people in resounding agreement.

Rowling was offering her blunt assessment of an article in Inc, which, in turn, referenced a much older Wall Street Journal piece.

In that story, writer Hilary Potkewitz outlined the many valid reasons why 4 a.m. is the ideal hour for getting things done.

For one thing, there aren't many texting, ringing, emailing distractions. It's possible, judging by how many people preface that hour with "ungodly," that even the lord himself isn't awake.

Another pre-dawn perk? Social media, the great time sink of our generation, is hardly stirring at all. No cute puppy videos nipping at your heels.

But the most winning endorsement for a 4 a.m. start time would be the cavalcade of famous doers who abide by it.

Apple CEO Tim Cook Apple CEO Tim Cook is wide-eyed and annoying at 3:45 every morning. (Photo: Laura Hutton/Shutterstock.com)

"Typically speaking I'm happiest, smartest, most creative and most optimistic between the hours of 4 and 8 a.m." Scott Adams, creator of the popular Dilbert comic strip, told CNBC.

And how do you discard the real-life examples of pre-dawn prodigies like Apple's Tim Cook or Richard Branson or M.I.T. president L. Rafael Reif, who sets his alarm for 6 a.m. but "I rarely get to hear it."

Well, you can dismiss them a la Rowling and go back to sleep.

Even better, once you've had your coffee and a nice danish at a more decent hour, you could summon a little science to your cause.

It turns out, there's plenty of evidence to suggest that you defy your internal clock at your own peril. A night owl who tries to shoehorn himself into a morning lark's world risks real health problems.

A recent study suggests everyone has a unique "chronotype"  — a biological rhythm that determines your preferences for when to wake up or go to sleep.

That's not so say you should burn the candle at both ends, either. A study published earlier this year noted that people who stay up late are at increased risk of everything from respiratory illness to psychological disorders to an early death.

Which leads us to the real issue that plagues us all — the lack of quality sleep.

And Tim Cook, dare we say you're not helping at all? At the very least, would you mind not making such a fuss in the kitchen? Some of us are trying to get some sleep.

Heroes get up at 4 a.m. every day
A lot of famous people get start their day at 4 a.m. But that doesn't mean you should.