Sugar cravings in the evening: what sleep, stress and hormones have to do with it

It has been a long day, dinner is over, and you are actually full. Yet an hour later you are standing in front of the cupboard looking for chocolate, biscuits or anything sweet. The next evening, the same thing. Sound familiar?

Sugar cravings in the evening rarely come down to just “too little discipline”. Sleep, stress, your daily routine and, in women, the menstrual cycle can all play a part. This article explains what research knows about this, what is more speculation and what you can do to narrow down the causes for yourself.

Sugar cravings in the evening: what happens in the body

Hunger and appetite are not the same thing. Hunger signals that the body needs energy. Appetite, that is, the desire for a particular food, is also driven by habits, mood, tiredness and the brain’s reward system. In the evening, a lot comes together: the day has taken its toll, the tension eases, and something sweet is quickly to hand. Several factors can intensify this moment.

Lack of sleep: when tiredness makes you hungry

Sleep is one of the best-studied influences on appetite. In a controlled study of young, healthy men, after just two nights of shortened sleep the satiety hormone leptin fell, while the appetite-stimulating hormone ghrelin rose. The participants were hungrier, and their appetite was directed especially towards high-calorie foods rich in carbohydrates (PubMed 15583226). However, the study was small.

A meta-analysis of several studies points in the same direction: after shortened sleep, participants ate considerably more on average without using more energy (PubMed 27804960). So if you regularly sleep too little, you may simply have a bigger appetite in the evening, and something sweet is then often the most obvious choice.

Stress and cortisol: food as a quick reward

Stress changes eating behaviour. A review article describes how the stress hormone cortisol and the brain’s reward system can interact: under stress, many people develop a stronger desire for very tasty, energy-dense foods, and eating has a calming effect in the short term. If this happens often, it can turn into a fixed habit (PubMed 17543357). The authors stress that these mechanisms are only partly understood in humans.

In everyday life, this means: if the cravings come mainly on demanding days, it is worth looking at the strain you are under, not just at the sweets.

Skipped meals and little protein during the day

If you eat nothing in the morning and just grab something quickly at lunchtime, you often come home very hungry in the evening. In a small study of young women with overweight who usually skipped breakfast, a high-protein breakfast reduced evening snacking on high-fat foods compared with skipping breakfast. A breakfast with a normal protein content did not have this effect (PubMed 23446906). This cannot simply be applied to everyone. But it is an indication that your daily routine influences how your appetite behaves in the evening.

Cycle and hormones: cravings before your period

Many women know sugar cravings in the days before their period. In a small study of female students, the desire for sweet, salty and high-fat foods such as chocolate and pastries was higher before menstruation than in the first half of the cycle. However, the amount actually eaten did not differ (PubMed 30485899). If your cravings follow a monthly pattern, that is a clue you can record in a diary and discuss with professionals.

Sugar cravings: gut bacteria and iron deficiency

Gut bacteria: Whether gut bacteria influence our eating behaviour is being researched. A review article puts forward the hypothesis that microbes in the gut could influence food cravings in various ways, for example via the vagus nerve or the reward system (PubMed 25103109). This is an exciting but early field of research. So far, there is no robust evidence that sugar cravings in humans are triggered by specific gut bacteria.

Iron deficiency: What is well described in iron deficiency is an unusual urge to eat or chew things that have no nutritional value (PubMed 35674869). By contrast, we have not found any robust studies on a link between iron deficiency and cravings specifically for sweet things. But iron deficiency can make you tired and exhausted, and tiredness in turn can influence appetite. That is why it can make sense to keep an eye on your iron status.

Measure instead of guess: what you can have tested

A food and sleep diary over two to three weeks is the simplest place to start: when do the cravings come, how did you sleep, how stressful was the day, what did you eat during the day, which day of your cycle are you on?

If stress and sleep are in the foreground, the Cortisol daily profile can show how the stress hormone changes over the course of the day. The laboratory measures cortisol in saliva in the morning, at midday and in the evening, plus DHEA from the morning sample.

The OM Vital blood test combines, in one capillary blood sample, ferritin as the storage marker for iron, the thyroid level TSH, blood lipids and vitamins such as B12 and D, among other things. It does not measure blood sugar or the long-term blood sugar level HbA1c. These levels are tested by your GP.

All levels are building blocks, not a diagnosis. Discuss them with your doctor, a naturopathic practitioner or the ORY expert team.

When you should have cravings checked by a doctor

Please have your blood sugar checked by a doctor promptly if your cravings come with severe thirst, frequent urination, unintended weight loss or persistent tiredness. Sudden cravings also belong in your doctor’s surgery if you take medication that affects blood sugar. Do not stop a prescribed medication without talking to your doctor first.

If you feel that you regularly lose control when eating, eat very large amounts in a short time or feel deeply ashamed afterwards, please talk openly about it with your doctor or a psychotherapy professional. Effective support is available for this, and it is not a question of willpower.

In brief

• Sugar cravings in the evening often have several reasons and are rarely just a question of discipline.
• In studies, too little sleep increases hunger and appetite.
• Stress can increase the desire for energy-dense food via cortisol and the reward system.
• Skipped meals and the menstrual cycle can play a role. There is hardly any evidence for gut bacteria and iron deficiency as causes.
• Severe thirst, frequent urination or weight loss should be checked by a doctor.

Frequently asked questions

How do I stop sugar cravings in the evening?

First observe your pattern with a diary: sleep, stress, meals during the day and your cycle. Getting enough sleep is a good starting point (PubMed 27804960), as are regular meals during the day. If you have warning signs such as severe thirst, have yourself examined by a doctor.

Why do I crave sugar at night?

Common reasons are a long day without enough meals, tiredness and stress. Shortened sleep can increase hunger and appetite (PubMed 15583226). If you regularly need to eat at night to get back to sleep, you should mention this to your doctor.

Can gut bacteria cause sugar cravings?

This is being researched but has not been proven. So far, there are mainly hypotheses about how gut microbes could influence eating behaviour (PubMed 25103109).

Are sugar cravings a sign of iron deficiency?

We have not found any robust evidence for this. In iron deficiency, what is described is rather an urge for things without nutritional value (PubMed 35674869). Whether your iron stores are sufficient is shown by your ferritin level.

Which hormones are behind sugar cravings?

Involved are, among others, leptin and ghrelin, which are influenced by lack of sleep (PubMed 15583226), the stress hormone cortisol (PubMed 17543357) and, in women, the hormones of the menstrual cycle (PubMed 30485899).

Is it normal to crave sugar before your period?

Many women report it, and one study found a stronger desire for sweet foods before menstruation (PubMed 30485899). If you have very severe symptoms before your period, you should raise this with your gynaecologist.

Sources

1. Spiegel K et al. Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med. 2004. PubMed 15583226
2. Al Khatib HK et al. The effects of partial sleep deprivation on energy balance: a systematic review and meta-analysis. Eur J Clin Nutr. 2017. PubMed 27804960
3. Adam TC, Epel ES. Stress, eating and the reward system. Physiol Behav. 2007. PubMed 17543357
4. Leidy HJ et al. Beneficial effects of a higher-protein breakfast on the appetitive, hormonal, and neural signals controlling energy intake regulation in overweight/obese, “breakfast-skipping“, late-adolescent girls. Am J Clin Nutr. 2013. PubMed 23446906
5. Souza LB et al. Do Food Intake and Food Cravings Change during the Menstrual Cycle of Young Women? Rev Bras Ginecol Obstet. 2018. PubMed 30485899
6. Alcock J, Maley CC, Aktipis CA. Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms. Bioessays. 2014. PubMed 25103109
7. Schnitzler E. The Neurology and Psychopathology of Pica. Curr Neurol Neurosci Rep. 2022. PubMed 35674869