By the time I was eighteen, I’d already been riding the rollercoaster of manic depression for two years. I was still at the beginning of a very rocky ride, still completely oblivious to the notion that my mercurial moods were caused by an illness. After the despondency of depression, my first floridly manic phase was a welcome relief. But too soon it spiralled out of control… without me even realising it.

For weeks, the recklessness had been building, the sensation that I was invincible and utterly unstoppable just growing and growing. Too long, I’d been trapped in a dark pit of despair; the freedom from it somehow made the wildness more intense.

For every coherent thought in my mind, there seemed a million more that weren’t, crashing together like a pile-up on the M1. The disco-ball rotating above the dance floor was hypnotising me, and my friends had a hidden agenda to get me drunk. Well, why not, it was my eighteenth birthday party after all, and Fibbers, our local club, had been hired for the night. It was invitation-only-entry, but as I gazed around the crowded club, I realised most of the people were complete strangers. Everything seemed overwhelming, and I wasn’t even drunk. Another drink was pressed into my hands; I grinned insincere thanks, waited until Tom walked away, and then poured the contents of the glass into the yucca plant beside me. I didn’t need alcohol to make me drunk; I was blissfully intoxicated by the brilliance of life itself, my head bursting with vibrant plans and foolproof schemes. Safely stored in my handbag were the tickets I’d purchased that afternoon for my impromptu trip to Memphis for Elvis week next month. Inside I was fizzling; the beat of the music had melded with the beating of my heart and I felt insuperable.

Hannah slid tipsily into the booth, her red hair a frizzy halo around her head. Her glasses were crooked on her face, and she was giggling hopelessly.

‘Having fun?’ she managed to gasp out, slopping her drink over the table. The party had been her idea. She knew somebody who knew somebody else who managed the club. The drinks weren’t free, but they were cheap. I smiled indulgently, every nerve in my body jangling.

The music stopped abruptly. Some fat bloke in a jumpsuit waddled out onto the pathetically small stage. A cheer went up as faces turned expectantly towards me. I stiffened, my facial muscles stubbornly refusing to shape the delighted expression that was expected of me. I stared in horror at the Elvis impersonator as he burst into an awful rendition of Blue Suede Shoes. He was a poor imitation of the real thing. My head spun with the volume of the backing track. The same thought kept pounding against the inside of my skull: He isn’t Elvis. He can’t be Elvis. I’m Elvis. Elvis is dead, and I am Elvis.

I stood up, hopping up onto the booth and vaulting the banister that stood between me and the pokey dance floor in front of the stage. ‘Elvis’ warbled on, oblivious. He finished Blue Suede Shoes and launched into Suspicious Minds. Or what was supposed to be Suspicious Minds – only the melody was distinguishable. He thought he was God’s gift, dancing, swinging his hips. The lights spun out of control. Red, green, purple, blue. Red again. Red like the lipstick painted on my lips, a clown smile. Red like blood. He curled his lip, trying to imitate the sneer. A new battery of thought against my skull: Red like his blood. Red. Red. Red. He’s not Elvis. I’m Elvis. He’s not Elvis. Others crowded onto the dance floor beside me, too drunk to notice the fury pulsing through my body. Some were even singing along, Tom amongst them. Tom, who should have known better.

‘Where’s the birthday girl?’ ‘Elvis’ shouted at the end of his song. Tom, laughing, pushed me forward. A really bad move. I was struggling to contain myself, struggling not to erupt, but as the people parted like the parting of the Red Sea, my anger swelled like a relentless wave.

A podgy hand was held out to help me up onto the stage. I stared at it, repulsed by the sight of it. I saw my own hand – my left one, my famous left hand – rising up from my side. And I watched, kind of impassively, as my fingers curled into a fist. My nails were getting too long, I noticed absently. Must cut them later.

‘Come on up here, Little Lady,’ ‘Elvis’ cajoled.

 The grin slipped from his face in slow motion as we both watched my hand coming up. He reeled back as my fist connected with that sneering mouth, the piggy eyes widening in shock. Red lights. Red blood. He’s not Elvis. I giggled. The collective gasp from behind me was comical. My hand returned obediently to my side as ‘Elvis’ concertinaed to his knees, and with my other hand, I seized the mic from the stand in front of him. I started laughing helplessly, but managed to splutter into the mic a phrase that had become a trademark for me during two years in the sixth form.

‘Ladies and Gentlemen, Elvis has left the building. Thank you and goodnight.’

The place erupted in laughter, though my friends – the dozen or so people there I actually knew – stared at me with half-veiled shock. For some reason, that only made me laugh harder, clutching the mic stand, doubled over in mirth. Behind me, ‘Elvis’ slowly rose to his feet, staring at me. The lips that he’d tried so hard to curl into the trademark sneer were beginning to swell; blood dribbled lethargically from the split in his bottom lip. The lights spun again. Green. He was an alien. I laughed harder.

‘You shouldn’ have done that, sweetheart,’ he slurred, the words running into one another. He sounded drunk. I was a volcano full of laughter instead of lava. Even as he advanced on me, it didn’t occur to me to stop laughing. I couldn’t stop laughing if I tried. I didn’t see the danger. It didn’t matter. I was invincible. Superman. No. Super-Elvis.

Tom snatched me out of harm’s way before ‘Elvis’ could swing his ape-like arm at me. I struggled to free myself as a fight broke out; I wanted to join in, but Tom held me back, his blue eyes no longer full of laughter.

‘Bloody hell, Marty,’ he swore, dragging me out of the club in the wake of everyone else sober and sensible enough to do the same. ‘I know you wanted a birthday to remember, but Christ Almighty! Why did you have to go and hit him?’

‘He’s not Elvis!’ I snapped. ‘I’m Elvis. It was a bloody insult. I had to stop him!’

Tom shook his head, his expression grave. ‘Oh God, not that again!’ he groaned.

I narrowed my eyes at him. ‘It’s true! It’s bloody well true and you know it. And what’s more, I’m going to Memphis to prove it!’

 Tom didn’t believe me. It turns out no one did. They all thought I was a little bit mad. Even the psychiatrist, when I told him four years later.

It wasn’t easy to accept I had an illness, but it helped to put six turbulent years of my life into some kind of perspective. And if there were, like Stephen Fry recently proposed, a button to take away Bipolarity, I wouldn’t press it for the world.