There is a particular hunger that arrives late. Not the hunger of dinner wearing off. Something more insistent than that, the kind that has you standing in front of the fridge at 11pm when you had no intention of being there, looking for something specific and not quite able to name it. Nothing about the day's food changed. The hunger did.

It is easy to file this under willpower. A late-week softness, a discipline that slipped. I want to write down a different reading, because the research points to one, and it is kinder and more accurate than the willpower story.

The hunger might be carrying a second message. And the second message is about sleep.

One molecule, two jobs

The hormone at the centre of this is ghrelin. Most people who have heard of it know it as the hunger hormone: it is made largely in the stomach, it acts on the hypothalamus, and it tells the brain to eat. That much is well established.

What is less widely known is that the same molecule does a second, unrelated-sounding job. Ghrelin also promotes sleep. A 2026 review in Frontiers in Psychiatry lays out both roles side by side: ghrelin stimulates slow-wave (deep) sleep and the growth-hormone secretion that happens overnight, at the same time as it stimulates appetite.[1] An earlier human study found that ghrelin promotes slow-wave sleep, and that after a night of sleep deprivation its overnight peak arrives significantly earlier than usual, as if the body were pulling the sleep-recovery signal forward.[2] Small sample, so I hold it loosely, but it is a clean illustration of the mechanism.

So this is not a hunger hormone that happens to also touch sleep. It is a single signal that the brain reads through two different systems. Appetite through one. Sleep pressure through the other. Same molecule, two receivers.

That distinction matters, and most coverage skips it. The common wellness framing is "sleep badly and you eat more," full stop. Accurate, as far as it goes. But it flattens the more interesting thing, which is that the very signal driving the late hunger is also a marker that the body is under-slept.

What a short night does to it

Here is where the evidence is strongest, and where I want to be careful about what it shows.

The landmark finding is old and much replicated. In a controlled study, curtailing sleep in healthy young adults raised circulating ghrelin by around 28 percent, dropped the satiety hormone leptin, and produced a measurable rise in hunger and appetite, with the sharpest increase in the desire for calorie-dense, high-carbohydrate food.[3] A later review traces the same pathway: less sleep, more ghrelin, less leptin, more subjective hunger.[5] And a 2020 meta-analysis, pooling across many studies, confirms the direction at the population level: short sleep is associated with elevated ghrelin, a small but statistically significant effect.[4]

There is also a suggestive detail about timing. A crossover study found that it was late-night sleep loss, losing hours in the second half of the night, that raised ghrelin and the desire for food. Losing early-night sleep did not do the same.[6] That is a single small study, so I treat it as a lead rather than a fact. But it is a notable lead, because the short nights the women MoMo is for tend to be late ones: the hours that go missing are usually the ones after midnight, not the ones before.

One honest caveat, and it is not a small one. Every one of the controlled studies above used only male participants, and the 2026 review names sex-dependent effects as an open question the field has not answered.[1] So I will not tell you this is how women's bodies specifically respond. The mechanism is described for humans in general, and the sex-disaggregated data that would let anyone say more simply is not there yet. That gap is worth naming rather than papering over.

The inference, held honestly

If you put the pieces together you get a clean-sounding story: you are hungry at 11pm because you are under-slept, your ghrelin is up, and ghrelin drives hunger. Each link in that chain is supported. But I want to be straight that no single study has traced the whole chain in a real kitchen at 11pm on a Thursday. The components are demonstrated separately. The line connecting them is a well-grounded inference, not a proven prediction.

I would rather give you the honest version than the tidy one. What the research supports is this: a body that has been short on sleep runs elevated ghrelin, and elevated ghrelin does two things at once. It asks for food, and it carries sleep pressure. The late hunger is real. It is not imagined, and it is not weakness. It is one signal being read loudly by the appetite system.

It is worth being clear about what this is not. It is not a rule that says the hunger is fake, or that the answer is to override it, or that anything in particular needs doing at 11pm. Hunger is information, not a verdict, and this post is not in the business of telling anyone what to eat or not eat. The only thing on offer here is a second way to read the signal.

A different story to tell yourself

What I keep coming back to is the frame, because the frame is where the harm usually is.

"I have no discipline at night" is a story that costs something to carry. "My body is running elevated ghrelin after an under-slept week, and that hormone drives hunger and marks sleep pressure at the same time" is a different story about the same evening. It does not fix the week. It does not make the hunger go away. But it moves the event out of the moral column and into the physiological one, which is where it actually belongs.

The women MoMo is for are, mostly, past the point of needing another tip. They know about protein and screens and wind-down routines. What is often missing is not a technique but a frame that stops handing the tiredness back as a character flaw.

So this is not advice. It is a noticing. The next time the late hunger arrives, more insistent than dinner would explain, it might be worth asking what the week's sleep has been doing underneath it. Not to correct anything. Just to know that the signal has a documented second meaning, and that reaching for food at 11pm after a run of short nights is a body doing something legible, not a person failing at something simple.

Noticing that a late-night hunger connects back to a week of short nights, so the pattern reads as a cycle rather than a verdict, is the kind of thread MoMo is built to hold across days. But that is a footnote. The essay is the signal, and the two things it is quietly saying at once.

References

Ditmer, M., Wojtera, A., Gabryelska, A., Turkiewicz, S., Białasiewicz, P., Strzelecki, D., & Sochal, M. (2026). Ghrelin's role in sleep and sleep deprivation: a narrative review. Frontiers in Psychiatry, 17:1744781. PMID: 41696469.
Schüssler, P., Uhr, M., Ising, M., et al. (2006). Nocturnal ghrelin, ACTH, GH and cortisol secretion after sleep deprivation in humans. Psychoneuroendocrinology, 31(8), 915–923. PMID: 16814473.
Spiegel, K., Tasali, E., Penev, P., & Van Cauter, E. (2004). Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Annals of Internal Medicine, 141(11), 846–850. PMID: 15583226.
Lin, J., Jiang, Y., Wang, G., et al. (2020). Associations of short sleep duration with appetite-regulating hormones and adipokines: A systematic review and meta-analysis. Obesity Reviews, 21(8). PMID: 32537891.
Van Cauter, E., Spiegel, K., Tasali, E., & Leproult, R. (2008). Metabolic consequences of sleep and sleep loss. Sleep Medicine, 9(Suppl 1), S23–S28. PMID: 18929315.
Meyhöfer, S., Chamorro, R., Hallschmid, M., et al. (2023). Late, but Not Early, Night Sleep Loss Compromises Neuroendocrine Appetite Regulation and the Desire for Food. Nutrients, 15(9), 2035. PMID: 37432152.