I've been on my feet for long stretches of time lately while waitressing in a busy restaurant the length of an Olympic swimming pool. This doesn't just involve humming around like a blue-bottomed fly but is also very stressful.

I enjoy waitressing enormously but have to work twice as hard as my colleagues as my mind can drift — I can charge someone £31 for a £351 lunch and then have to chase them down the street with the chip and pin. This all depletes energy resources, previously recharged — a little — when I did a job that involved sitting at a desk. Figures released recently show that Londoners work some of the longest hours in the UK, with an estimated one in six people putting in more than 48 hours per week.

For me, the effect of being on my feet for up to 15 hours a day finally began to take its toll. The first signs were obvious — fatigue and aching legs. The aching was alleviated by me lying in bed with cushions under my feet, thus lifting my legs above my heart to drain the blood pooled in my limbs. But then my heart started fluttering. At first I thought it was just the coronary adjustment you get after a sigh or a sneeze but it continued, giving me a vertiginous feeling that was far from pleasant. I thought it was a panic attack, perhaps induced by my increased caffeine intake. 

My emotions also seemed perpetually close to the surface, liable to overflow at any moment and in any form. Adrenaline surges saw me jittery and high, cackling like a hyena one minute, crying the next. I couldn't stop sobbing after getting the order wrong on table 10. I resorted to hyperventilating in the wine cellar until the head waiter came and peeled me off the Chianti Classico rack. He told me to take a stroll along the river and to breathe, which helped me gain a modicum of perspective. 

My general feeling was one that will be familiar to many stressed Londoners, of being under the cosh and unable to cope. I couldn't sleep either, despite throwing myself down like a slab of dead meat on my bed every night. Instead of sweet dreams I got floppy hands and feet. I was anxious and my heart was following an unfamiliar beat. Perhaps I was going to die?

It was with this doomy thought hanging over me that I decided 50 quid would be money well spent on a reflexology appointment. The one-hour session was initially uncomfortable as tender points in my feet indicated pressures and strains elsewhere in my body, but I gradually felt myself unfurl from tip to toe. Afterwards Kia, the skilled reflexologist, alerted me to what was wrong with my body — strained right knee, poor circulation, hormones and thyroid all over the shop, generally run down. She suggested I stop drinking coffee and start taking a vitamin B complex. Your body sops up vitamin B when you get stressed apparently, so it is very easy to be deficient.

I've never particularly believed in popping vitamins in bullet form — the preserve of American tourists who wear socks and sandals and monitor the passing week courtesy of a different pill for every day. Instead I've tried to eat a fairly balanced diet —enough greens, fruit and nuts to offset the chocolate fixes and the rich tarts and cakes at work. But I Googled vitamin B complex anyway and discovered it's a funny cluster of distinct vitamins that are often found together in the same foods — bananas, Brazil nuts, avocados, oats, beans, lentils, liver, nuts, meat, seaweed, potatoes, beer (well, brewer's yeast, anyway).  

Then I made a further foray to see how a deficiency might feel and it was like reading the last chapter of my biography — heart arrhythmia, numb hands and feet, erratic emotions, rashes, even thoughts about dying.

I told my friends and family about all this, to prove I wasn't simply a fruitcake, as they'd begun to believe. The guy I'm seeing was thrilled that there might be an end in sight to the floppy feet. Naturally I immediately bought a pot of vitamin B complex, unnervingly large and orange, and within three days I was feeling a bit better, not least because now I could throw my hang-ups over an alphabet letter, like kids do jackets at playschool. I still felt tired but was less likely to cry just because someone asked me if the rash on my hand was fake tan. 

Armed with this new information I felt the need to pass it on to everyone who seemed a bit below par and convert them to this new miracle cure for London's overwrought. I was surprised at how many of my friends were already taking some form of B supplement, notably those who had previously suffered from glandular fever or ME.  

One actress friend told me that when she was rehearsing a draining four-hour play, the entire (exhausted) cast were given B12 jabs. Apparently it did the trick and they sailed through the opening night and party, experiencing no hangovers and remaining marvellously insouciant about the poor reviews. I know Madonna takes B12 jabs, and gave Justin Timberlake one in his bottom (the best day of his life, apparently), but I had never entertained this as a possibility for us mere mortals.

Keen to expedite my recovery and achieve Madonna's perennial glow I booked an appointment with my GP and was given a shot of B12, 100 times the daily recommended dose, in my arm. Sadly I didn't feel instantly recharged: my eyes didn't start open or my hair gloss.

But over the next few days I definitely noticed energy seep back into my life, and felt more able to manage, less liable to crumple at the slightest push.

Amanda Griggs, director of health and nutrition at Balance Clinic, says that B vitamins deficiency causes adrenal fatigue as the adrenal glands feed on B vitamins when you're stressed, depleting your stocks. The body thinks it's being perpetually chased by a lion, so uses all its resources to cope with the stress — reducing energy levels and having an adverse effect on hair, skin and nails in the process. Griggs says that if you're lolling on a beach you could probably get sufficient B vitamins from your food but that if you're commuting to a 15-hour day in London you would benefit from a supplement. B vitamins are water soluble and any excess is passed out in urine, so there's no danger of overload if you eat extra B vitamins foods, too.  

From my brush with the imaginary lion on my back I can't recommend a dose of vitamin B complex more highly. London living can be unrelenting but it's great to know that when the wheels come off as spectacularly as mine did, something as simple as an accurate diagnosis and vitamin boost could get me coasting along again. It's certainly not a vitamin I'm going to be abandoning any time soon — at least not until I'm shining like linseed.

The B12 Jab

Injecting vitamins into your veins seems rather drastic, doesn't it? But apart from celebrities such as Tara Palmer-Tomkinson, Geri Halliwell and Charlize Theron — not to mention Justin — who reportedly demand the jabs for a quick energy boost, for some sufferers from B12 deficiency, it's the only solution.

I recently underwent a medical screening and discovered that I, too, am deficient in B12 — and this is making me anaemic. It's likely I have Pernicious anaemia — a condition in which the body is unable to absorb B12 through the gut.

As a consequence, supplements are ineffective but if left untreated my symptoms can include tiredness, headaches, palpitations, confusion and numbness. The solution for me is a 0.5ml injection of B12 into the upper arm or buttock once every three months.

For the B12 deficient, this should banish fatigue, but if you're not B12 deficient the injections are of no value. “You need about 2-5mcg of vitamin B12 a day,” says Dr Rosalind Smith of The Westover clinic in Kensington, where I underwent my tests.

“As long as you get that from your diet — usually meat and dairy — you won't obtain any additional benefit from B12 injections. Your liver stores a certain amount and after that, any excess is just peed out.”