You’re sitting in Science, overly tired from your all-nighter spent studying for your exam and become abnormally hungry. You aren’t sure as to why that is considering you had breakfast only one hour ago. You’ve heard it over and over again but probably haven’t thought much of it; is lack of sleep related to increased levels in appetite?

In an experimental study published in the Wall Street Journal, there were two studies in which two groups examined over the course of five nights. One group was females and the other males, both in their mid 30’s. In the first study, both groups slept a total of four hours every night. In the second study, the participants slept a total of seven hours every night. Before both studies took place, blood tests were taken to look at specific hormones related to hunger. For both studies the food intake was controlled on the first four days. The study does not point out what their diets specifically consisted of, so personally I think the possible confounding variables are numerous, such as the change in diet in which they are used to, the amount of food being eaten, what types of foods (whether they be loaded with fiber making them fuller for longer vs less fulfilling meals)…etc. If I were to conduct this study I would have changed their diets a month before to what they would be fed in the experiment, allowing their body’s to adjust to the new diet, and their responses in hunger. Anyways, back to the set up of the experiment, the last two days they let the participants eat whatever they wanted. The two studies were spread out over the course of three weeks, making sure that the previous study in which sleep was lessened did not affect the results of the other study. The results showed that those who had less sleep consumed more calories (300+) than those who had more sleep. In my opinion, the study was very well conducted and proved an accurate representation of the affect loss of sleep has on the human body’s digestive system and response. The study was able to prove causation because of the controlled environment, limiting intake as well as sleep levels, and because of the absence of confounding variables. However, it is important to note that the forced sleep could have been miscalculated, as you cannot exactly force someone to sleep on command, ultimately affecting the outcome.

The overall outcome of the experiment showed levels of the hunger stimulating hormone: gherlin, were higher in men compared to the woman after participating in the 4-hour-sleep study. So, does that mean this hunger affect only impacts males? Not quite, considering levels of GLP-1, a hormone that curves hunger and appetite levels, was lower in females than in males after the shorter period of sleep. On the fifth day of the experiment, when food access was not limited, each participant consumed 300 more calories than what they had during the 7-hour sleep study. (Lukits). So, although the hormones that are affected may differ between males and females, overall the lower the amount of sleep one gets greatly affects their levels in hunger making them hungrier than usual.

Overall, I think this experiment was very well performed. However, although this experiment was controlled, avoiding possible confounding variables, I think it is definitely possible that the placebo effect may have influenced the participants’ appetite. While being tested, they knew why they were being tested and what they were supposed to feel (boosts in hunger). This could have affected their choices, knowing in the back of their mind that they should have felt hungrier. Another possible confounding variable is stress. Stress hormones, like cortisol, can greatly affect appetite and may be one reason why those who consumed more calories did. Stress may also have increased due to the lower levels in sleep, causing the participants to eat more. An ideal study that would have worked better in proving causation would be a similar setting, but allowing the participants to begin a month early on their new diets so that their body’s could adjust. Another factor they should include is the types of food and amount of which the participants were fed.

There are many possible reasons why those who ate more did, as appetite is not such a black and white feeling. Some also eat out of boredom, which can explain the rise in calories as well. Next time you find yourself starving after a two hour night sleep, try to think if you are actually hungry, stressed, or bored. Maybe the answer relies on the person and circumstance more than the scientific evidence that may prove otherwise!