Katie Couric's Notebook: Obama's Birthday

President Obama is celebrating his birthday in Chicago tonight...home alone.

The First Lady and Sasha are in Spain, and Malia's at summer camp. On those rare nights we parents are truly on our own, we may exhibit what Carrie Bradshaw calls "secret single behavior." A mud mask. A marathon of Top Chef. Maybe staring in the mirror to find new gray hairs.

And the president admits...he sees a lot more grays these days.

The job has aged him, as it did his predecessors. Dr. Michael Roizen at the Cleveland Clinic stated constant stress can age the Commander in Chief two years for every one year in office.

So I guess that means he's really turning 50.

President Obama has enough stress to last a lifetime... and as he blows out his birthday candles, war, recession and a giant oil spill won't magically disappear.

But I hope he's able to take a break tonight, forget his troubles and spend time doing something he loves.

Happy birthday, Mr. President.

That's a page from my notebook.

I'm Katie Couric, CBS News.