Does Hunger Cause Insomnia?: How Appetite Affects Sleep

Common sense tells us that if we’re hungry, it’s logical for the body to remain alert in order to search for food, which may make sleep difficult.

Biology more or less backs up that line of thinking. Ghrelin, the hormone that controls appetite, is elevated when hungry and increases energy expenditure (1).

This isn’t a topic that’s been studied as much as you might think, simply because most people only go to bed hungry on strict diets or in the case of food insecurity.

Still, I’ve dug up as much relevant research as I could find, and I’ll walk you through the high level points that mostly show that hunger can cause sleep issues, and eventually lead to insomnia if it’s regular.

The Effect of Hunger on Total Sleep Time

One of the most important metrics of overall sleep quality is total sleep time. More is generally better (up to a certain point).

Here’s a quick biology lesson about 2 important hormones before we look at a study:

• Ghrelin - The “appetite” hormone. Ghrelin levels are high before a meal, and low right after.
• Leptin - Basically the opposite of ghrelin, it goes up after eating to signal that you’re full.

One study looked at the correlation between leptin, ghrelin, and sleep duration (2). A total of 1,024 subjects submitted blood samples first thing in the morning, and the most interesting finding was that high levels of ghrelin were associated with short sleep duration.

Because these measurements were taken in the morning, it’s a bit of a leap to conclude that people who woke up hungry also went to bed hungry, but it’s a reasonable hypothesis.

SummaryHigh levels of ghrelin, which indicates hunger, are correlated with short sleep duration. It’s as if the mind and body are saying “wake up and find us some food”.

The Effect of Hunger on Sleep Quality

It turns out that most people believe that not going to bed hungry is an important part of sleep hygiene. It’s something that most of us are taught growing up.

One study had subjects monitor the most important things they considered part of sleep hygiene while trying to implement them (3).

Sleep quality was measured both by the Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) and improved during the study.

Making the sleep environment more restful had a small effect, but the biggest improvements came from avoiding going to bed hungry or thirsty.

The main limitation is that we don’t know how much of a role thirst played in this experiment, which is important since dehydration can cause insomnia.

Finally, I wrote a summary of how calorie deficits can affect insomnia, but the gist of it is that calorie restriction can cause sleep trouble in the short term. It’s reasonable that calorie restriction would also cause some degree of hunger when going to sleep.

SummaryWhile more research is needed, the limited evidence available suggests that going to bed hungry lowers overall sleep quality.

The Effect of Sleep Deprivation on Hunger Hormones

Let’s look at ghrelin and leptin in a bit more detail.

Research suggests that poor sleep can also cause changes in the levels of these hunger hormones.

One study put subjects through monitored periods of restricted sleep and found that leptin levels became lower the following day, while ghrelin levels rose (4). 

In other words, poor sleep leads to increased appetite, which could cause some poor diet choices and lead to weight gain.

Being overweight is a main risk factor of insomnia, and this appears to be part of the explanation why.

It’s not surprising that another study showed that people tend to eat more after being sleep deprived (5).

Another experiment measured ghrelin levels at night and found that insomniacs have lower levels of ghrelin at night (6).

This struck me as strange as first, why would insomniacs have lower levels of hunger at night?

The most likely explanation is that this is the long term consequences of poor sleep. The poor sleep causes high levels of ghrelin during the day, and the excess eating causes lower levels of ghrelin at night.

Obesity can also cause hormone disruption, which may factor in here.

SummaryJust as hunger can cause poor sleep, poor sleep can then cause more hunger. It’s a vicious cycle that can lead to chronic insomnia over time.

Is It Better to Sleep Hungry or Eat Close to Bedtime?

Let’s say you’re going to sleep in 2 hours but are starting to get quite hungry.

Is it better to “suck it up” and go to bed hungry, or have something to eat.

I’ve written extensively before about how eating before bed can affect insomnia if you’re curious. The short version is that eating a lot before bed makes it significantly harder to get to sleep.

If you have to eat in the 2 hours leading up to bed, do it as early as possible and stick to a high GI healthy food like white rice or fruit.

SummaryIf someone is hungry enough to the point that it causes physical discomfort, it’s likely better to have a small snack of easy to digest carbohydrates.

Summary: Can Hunger Cause Sleeplessness?

The research we looked at suggests that hunger can cause sleep trouble, which can develop into insomnia over time.

With that being said, the research is lacking, and no research team has looked at this topic directly in a “healthy” population.

So while this conclusion seems reasonable, we can’t be too confident about it.

If you regularly find that you're hungry at night, but don't want to overeat, there are a few things you can do when you can't sleep when hungry.

References

1. Ghrelin: much more than a hunger hormone
2. Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index
3. Self-Monitoring vs. Implementation Intentions
4. Metabolic consequences of sleep and sleep loss
5. Increased Hunger, Food Cravings, Food Reward, and Portion Size Selection after Sleep Curtailment in Women Without Obesity
6. Nocturnal levels of ghrelin and leptin and sleep in chronic insomnia