I was feeling pretty run down. Had been for months – maybe a year – and I figured it was lack of sleep. This was new: I often sleep badly, but I’d never had problems with tiredness. But, you know, age. So I bought Night School, and worked through its recommendations. I put up blackout curtains. I cut out blue light. I timed my sleep to circadian rhythms.

It didn’t help. I got more sleep, sure, but still woke up with what I can only describe as a mushy head. The brain-feel that everything is further away than it should be. It was a dull weight at a particular point inside my skull, and it wouldn’t clear until lunchtime – if then. I started to wonder if I was massively run down. Or could I be stressed, but repressing it? Maybe I was ill.

It was none of these things. It was lack of sugar.

I wasn’t eating stupid amounts. A slice of cake after lunch. Shared office sweets in the afternoon – maybe a chocolate bar if someone was going to the shop. An M&S sponge pudding in the evening. I knew I had a sweet tooth – it’s a running joke at work – but it didn’t seem excessive.

Then one day I found myself feeling better earlier than usual. I eventually clocked that I’d had a couple of biscuits before lunch. A vague hypothesis started to form, and solidified over the next week as I tried having sugar at different times. Assuming I wasn’t placebo-ing myself, there was a clear pattern: if I didn’t have any sugar, the mushyhead was still there in the evening. If I had cake, things were a lot better.

Well. Didn’t like that. I’m not good with needing things. What if that thing goes away? Or what if I become properly addicted? It’s one of the reasons I don’t drink: alcohol is scary subtle, and I know where I’m vulnerable. But. What if the sugar was the only thing defeating the mushyhead? What was causing what?

In the end, my dislike of addiction won out. I went cold turkey, and had a shitty week. The mushyhead became permanent, and worse. This actually made me more determined – if things were that bad, I was doing the right thing. Even if it only helped a little in the end, I’d be better off.

Then a week later I woke up and everything was smooth. There was no mush. No weight. It was like I’d had an incredibly refreshing sleep. It lasted the morning, the day, the week. It’s lasted.

This honestly came as a shock. I hadn’t expected the mushyhead to go completely. I thought sugar was exacerbating another problem – I didn’t think it was the entire problem.

Sorry to sound like an advert, but I really can’t express how much better my life has been in the last couple of months. I can’t think of anything I’ve done that’s had such a big impact on my day-to-day life. I feel and think better. The mornings are pleasant. I’m probably nicer to be around. I’m definitely happier. Basically: wow.

Just to be clear: I am not joining the anti-sugar brigade, fashionable as that is. I don’t claim to speak for anyone other than myself. I can’t imagine this is a widespread problem – my reaction is probably abnormal. And I haven’t given up sugar altogether. My rule is: at weekends, after tea. That’s worked fine. (Plus, I’m not even 100% certain sugar’s the problem. It could be chocolate. I’m just not inclined to run the tests on myself to find out).

But, if you suspect you’re in a similar position, I really would recommend severely cutting back on the sugar and seeing what happens. Worked for me.