Ah, coffee! I used to drink pints of the stuff. Particularly when I got home from school. I had - and still have - a fabulous coffee machine which makes lovely espresso and I would have a coffee every half hour or so. It didn’t give me any major problems, but I was finding it hard to sleep and assumed it might be something to do with the caffeine. I was also getting some palpitations. These run in the family, but I was getting them quite strongly. I hadn’t realised caffeine could be a factor. I decided it might be worth trying to give it up.

I didn’t go cold turkey. I tried to, cutting everything out suddenly for a few days. But it didn’t work. I just craved Diet Coke constantly. So I decided to cut out my caffeine intake more gradually, and I changed my habits progressively over three months or so. But I realised that if I was going to do it properly it had to be all caffeine, not just coffee, so I stopped drinking tea and Diet Coke... everything. Then, once I was “clean” I gradually started allowing some caffeine products back in occasionally. I love having some bitter chocolate every now and then, and I might have a coffee once a week on a Saturday afternoon as a treat.

Giving up didn’t affect me in the classroom. When I’m with a class I’m too focused to think about anything else, and my working days are so packed that there’s not much time to think about cravings. I’m also lucky because I socialise in the prep room rather than the staffroom. Lots of people drink herbal teas there so it’s an easier environment. There’s not the smell of coffee to tempt me.

I’ve actually given up coffee twice. When I was in my twenties I was a vegetarian, and I was into yoga. I was a bit of a health freak. I cut out caffeine then, too, but it crept back in over the years. I’m still a bit of a gym bunny, so it’s important for me to look after myself, but I’m more relaxed about things. I found giving up easier the second time round.

I still think about a nice cup of coffee first thing in the morning when I get into school. I would love to let myself have one then. I have a cup of tea instead. There’s still a bit of caffeine, but it isn’t the same. And I do feel the benefit of having given up; I don’t get palpitations now.

For anyone trying to cut back or give up, I would say it needs to be gradual. Find an alternative you like; a herbal tea, perhaps. Then swap every other cup of coffee with it, and once you’re comfortable with that, gradually cut out more and more until eventually you’re caffeine free. But think about your total caffeine consumption; not just coffee, but teas and colas and everything. Caffeine is a drug and a stimulant. It has an addictive effect. To get rid of it, you have to be determined.

Gena Marsh is a chemistry teacher in Sheffield. She was talking to Steven Hastings