In August 2012, following a prolonged period of depression, I found myself unable to sleep for almost four days. With hindsight,  this was a turning point that made me realise I was properly ill, rather than just suffering from a severe case of the "blues". My illness eventually led to a two-month stay in a psychiatric hospital and a robust (so far…) recovery.

It's the time of year when it doesn't stay dark for long. I'm squatting on a corner of my bed cross-legged, like I haven't done since infant school. The brown Muji notebook is scribbled full of notes for what I know will be the greatest novel ever written.

My silk bedspread is so beautiful. I'm wearing just shorts, and the beads of sweat on my legs are diamonds catching sunlight. It's bliss. The rush of creative energy beats anything else I've experienced.

I have been awake for more than 50 hours. I know it's bad, but this fact feels small. I'm seeing the problem through a telescope turned round the wrong way. With nobody around to touch, I've hugged the shirts hanging in my wardrobe and reconnected with soft toys, evoking sensational memories of caravan holidays, Stickle Bricks and tiny infant school chairs.

Cooking is a waste of this magnificent creative time, but tortilla chips and Mini Babybel are heaven in my mouth. There's no desire in this place because everything is already perfect. No lust or hunger, just lightning thoughts and a stream of perfection from every touch, taste, sight and smell.

Seven months earlier a bomb went off in my head. A cliched midlife crisis, kicking in three days after my 40th birthday.

I've doubted everything. In my depressed mind what I've achieved counts for nothing and every flaw is a 12ft monster. I've told my therapist I've wasted my whole life. I've hung a noose under my kitchen stairs and beaten myself up for being too scared to put myself out of my misery.

So however fake it may be, my state of sleepless bliss feels like a reward. A day off from wanting to be dead. The facade starts to crack when I need to leave my house: it takes an hour to don T-shirt and jeans. Wallet, keys, mobile and Oyster card is the most confusing thing I've encountered since A-level maths.

Outside, I'm basking in sunshine. But friends and family are scared and an appointment has been made. I've now been awake for 70 hours. I mess up my taxi booking and end up taking a tube to Sloane Square.

A change at Victoria becomes an odyssey. I get a train going the wrong way, because direction signs and maps are just colours and lines. In a flash of angst, I think about jumping in front of the train. The Circle is the suicidal's line of choice, because most other tube lines have a trench under the rails.

A concerned friend is waiting outside Sloane Square. I cry when I see her.

"You haven't slept for how long?" she says, gripping my arm lest I stumble or attempt some crazy run into the path of a car.

"Do you realise you've just spoken for 20 minutes, almost without taking breath?" the psychiatrist points out.

I hadn't.

I'd read a ton of stuff online, and yearned to get the oh-so-fashionable bipolar diagnosis. The psychiatrist isn't convinced and says I have a textbook case of sleep deprivation, triggered by regular depression.

I get home with anti-psychotics to help stabilise my mood and benzos to put me to sleep. When I get into bed that evening, I've been awake for more than 80 hours.

The plan for the greatest novel ever written turns out to be 12 sides of barely legible drivel, but if someone asks about the happiest moment of my life, will anything ever beat the mentally deranged exhilaration of that hot August night?

• Robert Muchamore's latest book is Rock War (Hodder Children's Books).