Ask a Dietitian: Why Do I Crave Junk Food After a Sleepless Night?

Hi Jess, After a bad night’s sleep, I find myself constantly reaching for junk food throughout the day. It’s like I lose control of my eating habits when I’m tired and I’m not sure why. Can you help?

We’ve all been through those nights of tossing and turning, only to be woken up by the alarm when you finally manage to nod off. Strangely, after these nights, you may feel a pull towards junk food, let’s dig into why this happens.

Before we get to the factors at play, what does the research say?

Studies suggest that when we’re sleep deprived, our brain’s hunger signals are altered, making us crave high-calorie foods. In adolescents, less shut eye has been shown to alter nutrient intake, resulting in a rise in the percentage of calories consumed from fats and an increased intake of calories from snacks.

Similarly, in a study with women aged 18-55, a decrease of 33% in sleep was linked with heightened hunger, larger portion sizes, and stronger cravings for carbohydrate-rich and fatty foods.

So, what's going on here?

Well, insufficient sleep disrupts the hormones that govern appetite, the two key players being ghrelin and leptin.

Ghrelin, the ‘hunger hormone’ signals to your brain that you need to eat and refuel, while leptin, the ‘satiety hormone’ lets your brain know you’re full and satisfied.

However, these hormones are out of balance when you’re sleep deprived. There’s an increased release of ghrelin, while less leptin is present, leading to snacking, overeating and a preference for high-calorie foods.

Why do we succumb to junk food?

With these hormonal shifts at play, our brain's reward center becomes more sensitive to the pleasurable aspects of food. It’s no wonder we find ourselves naturally drawn towards choices that offer a quick dopamine release. Highly palatable foods, those sweet or salty snacks, fit the bill by triggering a rapid pleasure response when we’re tired and craving comfort.

If this resonates, here are some dietary habits to improve your sleep hygiene:

• Avoid caffeine. Whilst that cup of coffee may fuel your morning, it’s a stimulant that can disrupt your sleep. Opt instead for a herbal tea if you’d like a hot drink before bed.
• Limit alcohol. A nightcap may seem like a relaxing way to wind down, but it can disrupt your sleep patterns so be mindful of consumption before sleeping.
• Avoid heavy, spicy or sugary foods as these food choices can cause discomfort and disrupt your sleep quality.
• Tryptophan is an amino acid that helps produce serotonin, a neurotransmitter promoting relaxation and sleep. Consuming foods rich in tryptophan may improve sleep by boosting serotonin levels; nuts and seeds are great sources of these.

TL;DR

Don’t worry, you aren’t alone in craving junk food when you’ve had a sleepless night. A lack of shut eye messes with your hunger hormones. Grehlin, the ‘feed me’ hormone goes into overdrive, while leptin, the ‘I’m full’ hormone, takes a back seat. This results in you craving junk food for a quick pleasure fix.

There are a few habits to help though, such as ditching the caffeine and heavy foods before bed to aid a more restful sleep.