There's a reason why the question "It's 3. a.m. Who do you want answering the phone?" became a constant refrain of the 2008 election. The presidency is an all-hours, no-holds-barred job, and all that work and all that stress take a pretty significant toll on our leaders.
According to some researchers, it may even accelerate the aging process.
"You see it over a term," geriatric physician Ronan Factora told the Washington Post. "It's a good study of chronic stress on a person's overall health."
And if a time-lapse of President Barack Obama created by YouTube user Diran Lyons is any evidence, he's no exception. The video, above, races through a series of photos taken of Obama since he took office in 2009. And even though his expression remains pretty much the same throughout, the difference is clear: mid-presidency, Obama's face is much more lined, and his hair hair is much more grey.
The jury's still out as to whether chronic, presidential stress can actually age a person, but the Obama at the end of the video definitely looks much more like an Obama who has weathered national crisis after national crisis. We guess only time will tell.