My body is built of tissues which are built of proteins and fats and stuff. Proteins and fats and stuff are built of molecules which are made up of atoms in a variety of interesting arrangements. Periodically they end up in new arrangements due to ageing and digestion and other bodily processes which I pay minimal attention to, but they are still the same basic atoms and those atoms have been around since the dawn of existence.

Okay, granted my atoms have swapped electrons with like-minded atoms during the last several thousand or several billion years (depending on your point of view regarding the creation of life, the universe and everything), but essentially they are the same atoms. Come to think of it, all this swapping and changing of electrons means I have had sex - on an atomic level - with millions of people… just by existing. I've exchanged bodily fluids with a scant handful of partners, but I've exchanged atoms with kings and commoners and (now this really grosses me out) with corpses, critters, cars and concrete all thanks to promiscuous atoms.

Never mind their indiscriminate sexual habits - hydrogen sharing electrons with oxygen, potassium having a hissy fit and making a molecular threesome with dihydrogen oxide and organic molecules string together in some damned atomic orgy - my atoms are tired. Who wouldn't be after a lifetime spent exchanging electrons with almost anyone they bump into? After all the millennia some of those atoms have contracted atomically transmissible states and spend their time ion positive or ion negative.

Phew! I may only be 35 years old, but my body is built of the same atoms which existed at the dawn of time and they've spent the whole intervening time in an orgy of electron sharing and partner swapping. No wonder I'm tired - my atoms are tired! I'm not so much bone tired as atom tired.

Ever since they popped into existence, my constituent atoms have been wide awake, zipping about in one body or another, swapping electrons when they bump into likeminded atoms and generally not getting a wink of sleep because even when a body is dead and buried, its atoms are busy forming new and putrescent compounds due to the decay process.

Let's face it, my body is tired at the atomic level. But will my employer accept that on a sickness form?