Four hours’ sleep. By half nine the next morning I’d been through the crisps twice.
Second day running. I told myself it was a discipline thing, that I just needed to try harder. Not the first time I’d had that thought either.
Here’s what got me. By that point I’d been doing the Rhythm Reset for months. tracking blood tests going back to 2012, biomarkers, food logs. I know exactly what a bad food choice looks like on paper. Knowing didn’t stop my hand going back in the bag.
It took me an embarrassingly long time to spot what was actually happening. Not a willpower problem. A hormone problem. And once I saw it, three separate weeks over two months suddenly made complete sense.
The Pattern I Kept Missing
Day 5 of the Rhythm Reset. Weight held at 13 stone 10, same as it had been for a week. Energy 6/10. Mood, oddly, 8/10. I’ll come back to that one.
Four hours’ sleep the night before. Not planned, just happened. By mid morning I’d been through half a family bag of crisps. Second day in a row.
My own conventional wisdom said I should know better. I’d logged enough fasting windows and enough food to know exactly what a bad choice looked like on paper. Knowing didn’t stop my hand going back in the bag.
It wasn’t a one off either. Three weeks later, a hospital appointment got cancelled after I’d walked three and a half hours to kill time. Came home starving, and a full tub of millionaire shortbread was gone. Roughly 2,000 calories. I wasn’t even hungry in the normal sense, just running on nothing.
A few weeks after that, a day out of surgery. Two hours’ sleep, anaesthetic still doing its thing. Bought a packet of chocolate hobnobs to line my stomach before the painkillers. Told myself one or two. Three quarters of the packet gone before I’d properly registered I was eating them.
Three separate weeks. Three separate reasons on paper: stress, boredom, drugs wearing off. Same trigger underneath every single time. Took me a stupidly long time to see it.
What Was Actually Happening in My Blood and Hormones
Seventeenth of October, logged as WMTWL-EVID-0147. Four hours’ sleep. Energy 6/10. Weight held at 13 stone 10 despite the crisps, which is odd on its own. Ghrelin up, leptin down. That’s logged, not guessed at.
Sixth of November, fourth night running on four hours. Weight had dropped slightly to 13 stone 8.5. Same story, sleep gone, hunger hormones doing what they do. This time it wasn’t crisps, it was the whole tub of shortbread.
Twenty second of November, two hours’ sleep, post surgery. Twenty two months into this by that point. Four and a half stone down. Off every medication since February 2024. And I’m sat in the car with a packet of hobnobs going down without me really deciding to eat them.
That’s the bit that actually rattled me a bit. Not the crisps, not the shortbread. The fact that twenty two months of doing this properly hadn’t switched it off.
I’d assumed, wrongly as it turns out, that enough months of good habits eventually overwrites the bad pattern. That’s not really how it works. The pattern doesn’t disappear, it waits for the conditions that trigger it. And the condition, every single time across three completely different weeks, was short sleep.
Peter Attia, the longevity doctor who wrote Outlive, cites research on exactly this. Chronic sleep deprivation suppresses leptin and raises ghrelin, and people end up eating roughly 300 extra calories the next day, specifically reaching for high sugar, high fat food. Not random extra food. Specifically the stuff I was reaching for. Crisps. Shortbread. Hobnobs.
Ghrelin is the hunger signal. Leptin is meant to be the “you’ve had enough” signal. Four hours’ sleep and the two of them basically swap roles for a day: hunger goes up, satiety goes quiet. Not a mood. Not a discipline failure. The actual chemistry doing the opposite of what you need it to do.
The Leptin Light That Doesn’t Know When to Stop
This wasn’t one lightbulb moment, and I’d like to say it was because it makes a better story, but that’s not what happened. It was slow. Podcasts, mostly, a few books, bits landing here and there over months until the ghrelin-leptin thing stopped being someone else’s science and started sounding like my own Tuesday. It wasn’t until I sat down and lined up the three dates properly that it became an actual pattern rather than a vague feeling.
I call the ghrelin hunger wave “The Tantrum”, the same spike that hits around hour sixteen to twenty of a fast. Turns out it’s the same tantrum here. Different trigger, bad sleep instead of a long fasting window, same hormone throwing the same strop.
Here’s the leptin bit that took me a while to get my head round. Think of your loo cistern with the little float on an arm. When the tank’s full, the float sits high and shuts the valve off. Flush it, the water drops, the float drops with it, the valve opens back up. Brilliant system, but only in one direction. It’s very good at spotting “empty, fill me up.” It’s not built to notice “actually, that’s plenty, stop.”
Leptin’s the same. It’s a low fuel light, not a full tank light. Sleep deprivation can trip that low fuel signal even when nothing’s actually changed about your fat stores. The tank hasn’t emptied, the float’s just been knocked down anyway.
What this suggested to me, and this is one person’s data, not a study, was that willpower was never really the variable. The sleep was the variable. Every time sleep dropped below about six hours, the hunger signal misfired, regardless of what else was going on that week. Stress, boredom, anaesthetic: different costumes, same underlying trigger.
This Isn’t a Discipline Problem
The advice most of us carry around is simple: if you keep making the same “mistake,” it’s a willpower issue. Try harder next time. And on the surface that makes sense, it’s the obvious conclusion if nobody’s ever explained what ghrelin and leptin actually do on a short night.
Nobody really explains it, mind. Not because anyone’s hiding it. GPs have ten minutes and a room full of guidelines that were mostly written before this research caught up. It’s simply not the kind of thing that comes up at a normal appointment.
So if you’ve been telling yourself the same thing I told myself, that you know better and should just be stronger than the biscuit tin, it might not be a character problem at all. It might be a hormone that’s had four hours’ sleep, doing exactly what four hours’ sleep makes it do.
What I’d Watch For Now
If I’m starting this over, the thing I’d watch for earlier isn’t “am I being disciplined today.” It’s “how did I sleep last night.” Not always an easy one to answer, sleep isn’t something you can just decide to have more of. Some weeks it’s there, some weeks it isn’t.
If you’re already tracking your own data and notice cravings spiking specifically the day after a short night, not every bad day, specifically the post bad sleep ones, that’s worth mentioning to your GP as part of the bigger picture. Not a diagnosis. Just a thread worth pulling.
Awareness doesn’t fix it, for what it’s worth. Twenty two months in and I still lose to the hobnobs sometimes. But it does give me the choice. Sometimes I catch it now, sometimes I don’t.
So here’s what I’d leave you with. If you keep “failing” at the evening snacking thing no matter how hard you try, when did you last actually look at your sleep instead of your willpower?
🎯 Key Takeaways
- It’s not always willpower: short sleep suppresses leptin and raises ghrelin, which can misfire hunger signals regardless of how disciplined you normally are
- The pattern repeats under different disguises: stress, boredom, and anaesthetic all triggered the same response, the common thread was sleep under six hours
- Awareness doesn’t switch it off: even 22 months into a documented transformation, short sleep still triggers the same craving pattern
- Leptin is a low fuel light, not a full tank light: built to notice when reserves are empty, not to reliably signal “enough,” which is why sleep loss can trip it even when nothing else has changed
- Track sleep alongside cravings: noticing the day-after-bad-sleep pattern is useful information for a GP conversation, not a discipline test
Want to Track Your Own Sleep and Hunger Pattern?
If you’ve noticed cravings spike after a bad night and want to see whether it’s a genuine pattern rather than a rough week, the 14-Day Rhythm Reset Guide includes a simple version of the tracker I use to log sleep, energy, and hunger side by side.
👉 Get the 14-Day Rhythm Reset Guide (free)
💪 Want ongoing support? Join Rhythm Club for £30/month (includes FREE app access, community, and weekly accountability calls)
⚠️ Important: This is educational content based on evidence and personal experience. It is not medical advice. Speak to your GP before making changes to your fasting pattern, diet, or medication.
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