Why you crave junk food when you’re tired and how a healthy diet can fight fatigue

Why you crave junk food when you’re tired and how a healthy diet can fight fatigue

Do you find yourself craving crisps, candy or doughnuts instead of a healthy snack when you’re sleep-deprived and feeling fatigued? You’re not alone, and you’ll probably be happy to know it’s a natural physiological response. Still, if you want to fight off fatigue, you’ll have to put a little planning into the types of snacks you have on hand when tiredness and cravings strike.

At least this is the finding of a recent study1 conducted by Dr Maryam Hamidi, PhD and researchers at Stanford University. 

As a nutritional scientist, Hamidi’s interests lie in exploring the complicated relationship that exists between sleep and diet. Sleep deprivation comes with the territory for most physicians and healthcare workers who often work long hours and experience interrupted sleep due to shift cycles. While most research has examined methods to improve sleep by rearranging schedules or reducing working hours, few have examined how dietary modifications may help. So, in their latest study, Hamidi and her team examined a wellness survey completed by 245 Stanford physicians to determine the associations between dietary habits and sleep-related impairment (SRI).

Sleep-related impairment in this context refers to perceived functional impairments experienced during waking hours that are associated with sleep issues or diminished alertness2

From the survey data, the team identified three dietary patterns:

  1. Plant-based
  2. High protein
  3. High saturated fat and sugar

The findings revealed that the more physicians consumed a plant-based diet, the less likely they were to report sleep-related impairment. Conversely, the more saturated fat and sugar that they consumed, the higher the reports of sleep-related impairment. High protein diets did not affect SRI scores either way.

While the study’s outcomes relate specifically to physicians in this instance, they’re not limited to them. Anyone who suffers from sleep deprivation, from college students to new parents, pilots and shift workers, may experience similar cravings for junk food when feeling fatigued.

Craving junk food when tired

Why do we crave junk food when we’re tired?

Previous scientific studies have explored the multiple possible causes that lead to junk food cravings when people are fatigued, as well as the links between sleep deprivation and obesity. Most explanations point to physiology as the primary cause.

For many, chocolate and candy are the go-to options when energy levels tank, and this makes physiological sense. Sugar provides a quick energy fix by boosting blood sugar levels. Add to this the fact that when we’re tired, we have lower executive brain function, so our decision-making ability and willpower3 is impaired. This means that we’ll almost always choose these types of unhealthy snacks over healthier options like fruit that could offer an equivalent energy boost.

Research also indicates that a lack of sleep can also alter appetite-regulating hormones4 (ghrelin which stimulates appetite and leptin, which reduces it) as well as metabolism and brain function5. This causes cravings for high calorie, high sugar, high fat and salty snacks in an attempt to boost energy levels. 

All of these factors work together to drive us to eat unhealthy foods. The issue is compounded when we find ourselves in professions or situations that make it difficult to access and eat healthy food.

Eating healthy to fight fatigue

How healthy eating can help to fight fatigue

Numerous studies have established an intricate link between diet and sleep. What we eat and when we eat it can affect the quality of our sleep, but likewise, the amount of sleep we get can affect what we want to eat.

Different foods are converted into energy at different rates. Snacks like chocolate and sweets provide a rapid energy boost. The problem is that when we reach for these instead of low glycaemic index (GI) sources of carbohydrates (i.e. carbohydrates that are broken down into sugar more slowly), the body suddenly gets more sugar than it requires. Insulin is produced in an attempt to compensate and balance sugar levels. This, in turn, causes blood glucose (i.e. blood sugar) to decrease, which leads to a sudden drop in energy levels and feels of fatigue6

Low fibre, high saturated fat diets can also reduce the amount of deep, slow-wave sleep that you enjoy during the night. Consuming excess sugar can also lead to unwanted midnight waking.

When options like whole grains (things like brown rice, barley, quinoa, buckwheat, bulgar wheat, oatmeal and whole-wheat bread) and healthy unsaturated fats (avocados, olives, olive oil, natural peanut butter, fatty fish and nuts) are consumed, these are broken down and release energy more slowly. This ensures that your body has the reserves it needs to draw on throughout the day7. This helps to prevent energy slumps and feelings of fatigue during waking hours.

What’s more is that a healthy, balanced, high-fibre diet that is rich in fresh fruit and vegetables, whole grains and low-fat protein and low in added sugars, can not only help you to fall asleep quicker but also help you to get more sleep8, 9

If you’re prone to fatigue due to your personal or working circumstances, aim to cut back on sodas and high-sugar, salty and saturated fat-laden snacks. Instead opt for fruit, vegetables, nuts, smoothies or even healthy protein bars. Doing so can help you to reduce the brain fog, concentration difficulties and feelings of irritability caused by poor sleep.



1. Hamidi M, Shanafelt T, Hausel A, Bohman B, Roberts R, Trockel M. Associations Between Dietary Patterns and Sleep-Related Impairment in a Cohort of Community Physicians: A Cross-sectional Study. Am J Lifestyle Med. 2019:155982761987192. doi:1177/1559827619871923
2. PROMIS – Sleep-Related Impairment.; 2019:1. http://www.healthmeasures.net/images/PROMIS/manuals/PROMIS_Sleep-Related_Impairment_Scoring_Manual.pdf. Accessed November 1, 2019.
3. Pilcher J, Morris D, Donnelly J, Feigl H. Interactions between sleep habits and self-control. Front Hum Neurosci. 2015;9. doi:3389/fnhum.2015.00284
4. Taheri S, Lin L, Austin D, Young T, Mignot E. Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. PLoS Med. 2004;1(3):e62. doi:1371/journal.pmed.0010062
5. Greer S, Goldstein A, Walker M. The impact of sleep deprivation on food desire in the human brain. Nat Commun. 2013;4(1). doi:1038/ncomms3259
6. Carbohydrates and Blood Sugar. Harvard School of Public Health. https://www.hsph.harvard.edu/nutritionsource/carbohydrates/carbohydrates-and-blood-sugar/. Accessed November 1, 2019.
7. Youdim A. Carbohydrates, Proteins, and Fats - Disorders of Nutrition - MSD Manual Consumer Version. MSD Manual Consumer Version. https://www.merckmanuals.com/home/disorders-of-nutrition/overview-of-nutrition/carbohydrates,-proteins,-and-fats. Published 2019. Accessed November 1, 2019.
8. Follow These Healthy Eating Habits for a Good Night's Sleep Tonight | Sleep.org. Sleep.org. https://www.sleep.org/articles/eat-to-sleep-better/. Accessed November 1, 2019.
9. St-Onge M, Mikic A, Pietrolungo C. Effects of Diet on Sleep Quality. Advances in Nutrition. 2016;7(5):938-949. doi:10.3945/an.116.012336