Understanding Nutrition: Why Do We Feel Hungrier After a Short or Poor-Quality Sleep? ── The Mechanism of "Sleep-Deprived Food Fight" Created by Hormones and the Brain

1. The Mystery of "Lack of Sleep and Appetite" Covered by Le Progrès

The French newspaper "Le Progrès" addressed the theme
"Pourquoi a-t-on faim après une courte ou une mauvaise nuit de sommeil ? (Why do we feel hungry after a short or poor night's sleep?)"
in its health column dated November 15, 2025.leprogres.fr+1

The article begins with relatable "common experiences" that many people might identify with.

• After an all-nighter, sweet pastries and sugar-laden café lattes look unusually appealing in the morning

• On days when you haven't slept well, you feel like snacking all day

• When you go to the supermarket, you end up putting more snacks and sweets in your basket than usual

According to a study by Chapman et al. from Uppsala University in Sweden, cited by Le Progrès (2013),even one night's lack of sleep can make people prone to overeating "both in quantity and quality." Participants shopped for a "week's worth of groceries" in a virtual supermarket on days when they had slept well and on days after staying up all night. The results showed that after staying up all night,

• the total calories of the foods placed in the basket increased

• they chose more high-fat, high-sugar foods

• and were willing to purchase them even if they were expensive

This tendency was observed.leprogres.fr+1

The article highlights two hormones, **"ghrelin" and "leptin,"** as keywords behind this behavior, explaining the deep connection between sleep and appetite.

2. Appetite Hormones "Ghrelin" and "Leptin": What Happens Overnight?

2-1. Ghrelin: The "Hunger Hormone" That Makes Your Stomach Growl

• A peptide hormone mainly secreted from the stomach

• When blood levels rise, it acts on the hypothalamus to enhance the sensation of "hunger"

• It typically rises before meals and falls after eating

Ghrelin is known not only for inducing the sensation of hunger but also formaking people more likely to prefer high-calorie, fatty foods.Ask The Scientists+1

2-2. Leptin: The "Satiety Hormone" Secreted from Fat Cells

• A hormone secreted from body fat

• It signals the brain that "energy is sufficient," putting a brake on appetite

• At night, leptin levels are high,adjusting so that you don't wake up hungry while sleeping.

The French health magazine for seniors, "Notre Temps," also explains that
"when sleep duration is shortened, ghrelin increases, leptin decreases, and this imbalance leads to strong hunger and increased appetite."
.Notretemps.com+1

2-3. The Combination of "Ghrelin↑ and Leptin↓" Caused by Lack of Sleep

In experiments where sleep time was limited to about 4-5 hours,

• ghrelin increased (hunger signals became stronger)

• leptin decreased (the satiety brake weakened)

These changes have been consistently reported.Notretemps.com+2Ask The Scientists+2

A report compiled by the French sleep specialist institution "Institut du Sommeil et de la Vigilance" also introduces that
"after lack of sleep, hunger and carbohydrate intake increase, and overall energy intake increased by about 22%."institut-sommeil-vigilance.org

In other words, the day after lack of sleep, it is easy to be in a state where **"even if the body's energy is sufficient, the hormonal balance mistakenly perceives it as 'insufficient.'"**

3. It's Not Just Hormones: The Brain's "Reward Circuit" Also Goes Haywire

The Le Progrès article touches not only on hormonal changes but also onchanges in brain function regarding the study by Chapman et al.leprogres.fr+1

3-1. Excessive Response of the Reward System

Brain imaging studies on sleep-deprived subjects have shown that

• when they see high-calorie foods (pizza, donuts, cakes, etc.)

• the activity of the reward system (nucleus accumbens, striatum, amygdala, etc.) becomes stronger than when they have slept well

.Science et vie+1

In other words, the sleep-deprived brain is in a state where it easily perceives **"junk food = an incredibly attractive reward."**

3-2. The Power Down of the Prefrontal Cortex, the Command Center of Reason

On the other hand,the activity of the prefrontal cortex, known as the "command center of reason," decreases, and

• "Let's take it easy today"

• "This is high-calorie, so let's choose something else"

suchlong-term health and weight-conscious braking decisions become less effective.Science et vie+1

At the hormone level, ghrelin urges "eat more,"
at the brain level, the reward system cheers "junk food is the best!",
and the prefrontal cortex silently agrees, "Well, maybe just today."

This triple combo is the true nature of the "unstoppable appetite" that occurs the day after lack of sleep.

4. Cortisol and Insulin: The Vicious Cycle of Stress and Blood Sugar Levels

4-1. Cortisol: The Hormone Raised by Stress and Lack of Sleep

Sleep deprivation and intermittent sleep increase the secretion of the **stress hormone "cortisol."**Notretemps.com+1

Cortisol is originally necessary for

• waking up in the morning

• maintaining blood sugar levels

• coping with stress

but when it remains high for a long time, it can

• increase cravings for sweets and fatty foods

• make it easier to accumulate visceral fat

. Sleep deprivation is precisely a condition that easily leads to this "chronic cortisol elevation."

4-2. Insulin Resistance: Blood Sugar Levels Become More Prone to Fluctuate

Continued lack of sleep has been reported in various studies to easily worseninsulin resistance.Notretemps.com+1

• Insulin becomes less effective

• Blood sugar levels become prone to rapid rises and falls, creating a "fluctuating" state

• When blood sugar levels drop suddenly, strong hunger and drowsiness are more likely to occur

As a result,

"Feeling sluggish from lack of sleep → temporarily boost with sweet drinks or pastries → quickly drop again and want more"

leads to ablood sugar roller coaster state.

5. In the Long Term, Risks of Obesity, Metabolic Syndrome, and Diabetes

The Le Progrès article itself is a relatively short column, but there are many epidemiological studies in the background.c10i.com+3leprogres.fr+3instit