Does Junk Food Cause Insomnia? Here's What the Science Says...

You have a fairly late night snack of chips, cookies, or some other junk food, and then you find yourself unable to get to sleep later.

Does that sound familiar?

If it’s enough of a routine, these sporadic sleep problems can develop into chronic insomnia, which then causes many side effects.

We’re going to look at the different ways that research links junk food consumption with sleep problems.

Why is Eating Junk Food Causing Insomnia All Of a Sudden?

One thing to address right off the start is that even if junk food consumption frequency hasn’t changed, it can still contribute to sudden insomnia.

There’s a certain level of general “stress” (mental and physical) that we can take while still sleeping well. The negative effects of eating junk food contributes to that stress level.

If you stay below your metaphorical insomnia threshold, sleep should be fine. But having habits like eating junk food puts you close to that threshold, and one little change can put you over the line.

It could be as small as eating junk food a bit closer to your bedtime, a temperature change, or a small extra amount of stress in your life.

SummaryEating junk food regularly adds to your typical stress levels, which can leave you vulnerable. Even a small change out of your control can make it seem like insomnia came out of nowhere.

The Effect of Junk Food on Gut Microbiota

There’s a few different ways that junk food can potentially cause sleep trouble.

The first is that the more junk food you eat, the more it affects your gut microbiota (the bacterial environment in your gut) (1).

That may not seem like a big deal, but recent research shows that the gut can directly affect brain function through the brain-gut-axis (2).

Having an unhealthy gut can lead to impaired neurotransmitter control. It’s the same mechanism that explains how probiotics can affect sleep.

SummaryWhile gut research is still relatively new, it shows that our gut health is connected to our mental health. Our gut health is primarily affected by the quality of the food we eat (among other factors like stress).

Junk Food and Mental Illnesses

Whether it can be solely explained by gut health, several studies have found that frequently eating junk food is linked to mental illness (3).

And mental illnesses, particularly depression, are common causes of sleep problems.

In children, one study found that the children who ate more junk food had later bedtimes and poorer sleep quality (4).

Another study found (5):

Junk food consumption may increase the risk for psychiatric distress and violent behaviors in children and adolescents

One study looked at the effects of both energy drink consumption and junk food and mental health (6). It found that both junk food and energy drink consumption resulted in a greater risk of multiple mental health conditions like stress, depressive mood, and sleep dissatisfaction.

The subjects most at risk were those who consumed both junk food and energy drinks regularly.

Finally, food addiction also comes with an increased risk of poor sleep quality (7).

Junk Food, Obesity, and Sleep

Obesity is one of the biggest risk factors for insomnia.

Obviously you can eat junk food without being overweight or obese, but if you develop any weight issues, it’s raises your chances of having sleep issues (8).

Sugar and Insomnia

Not only does sugar make it easier to gain weight, there’s evidence that sugar can cause insomnia in some cases.

Several studies have found that poor sleep quality is directly linked to the amount of sugar consumed, particularly in students with insomnia (9, 10).

Sugar increases insulin resistance, and research shows that insulin resistance contributes to short sleep duration and insomnia (11).

SummaryFrequent junk food consumption has side effects like inflammation, insulin resistance, and weight gain; all of those can cause sleep issues.

Summary: Can Junk Food Cause Sleep Problems?

There’s a lot of research showing that long term junk food consumption comes with a higher risk of sleep issues and insomnia. If you want to sleep well you'll need to eat healthy, at least somewhat healthy.

Other than eating a large amount of sugar or fat before bed, sleep troubles are typically not caused by one-off junk food snack.

The tolls that junk food takes on your physical and mental health only become clear over a longer time period.

However, keep in mind that correlation does not equal causation. Someone might start having sleep issues and associate them incorrectly with eating certain junk food. There are many other possible causes of insomnia that should also be ruled out. 

References

1. Adherence to the Mediterranean diet is associated with the gut microbiota pattern and gastrointestinal characteristics in an adult population
2. Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour
3. Junk Food Consumption and Symptoms of Mental Health Problems
4. Associations between self-reported sleep measures and dietary behaviours in a large sample of Australian school students
5. Association between junk food consumption and mental health in a national sample of Iranian children and adolescents
6. Association between energy drink intake, sleep, stress, and suicidality in Korean adolescents
7. Prevalence of food addiction and association with stress, sleep quality and chronotype
8. Childhood obesity, prevalence and prevention
9. Relationship Between Added Sugar Intake and Sleep Quality Among University Students: A Cross-sectional Study
10. Sleep duration and consumption of sugar-sweetened beverages and energy drinks among adolescents
11. Sleep disturbances and insulin resistance