Does Melatonin Cause Weight Gain? What Research Shows

First things first: taking a melatonin supplement does not cause weight gain. In fact, taking melatonin has been associated with lower body weight (6).

What is a concern, however, is whether melatonin deficiency can cause weight gain. Research has indicated a correlation between low melatonin levels and weight gain. In a 2014 study, low levels of melatonin were associated with a higher appetite and an increase in weight. Interestingly, the participants were able to lose weight again when they began taking a melatonin supplement (7). Another study, conducted on lab rats, found that low levels of melatonin can interfere with your body’s fullness signals, increase your cravings, increase your weight, and prompt you to eat more (8).

Of course, preventing this problem begs the question of why you might have low melatonin levels in the first place. There are a whole host of possible culprits. Screen time late at night can throw off your circadian rhythm (9). Illnesses and conditions like dementia, mental health issues, cancer, type 2 diabetes, and more can decrease melatonin levels (10). On top of that, melatonin naturally decreases with age (11)! So you may owe your melatonin deficiency to the simple passage of time.

If your melatonin levels are low, there are six simple things you can do to keep your sleep quality up and your weight down.

1. Get Full-Body Sun Exposure

Did you know that exposure to bright sunlight in the morning (without sunglasses) activates your nocturnal melatonin production sooner, which helps you fall asleep more easily at night?

Spending time in the sun is one of the best ways to regulate your circadian rhythm, combat insomnia, ease PMS symptoms, and treat seasonal affective disorder (SAD). Strive for 30 minutes of sunshine first thing in the morning (without sunglasses). Then once noon hits, head back outside for an hour to soak up even more benefits (12, 13).

Here's what melatonin researcher, Russel J. Reiter of the University of Texas Health Science Center, has to say about melatonin...

"The light we get from being outside on a summer day can be a thousand times brighter than we’re ever likely to experience indoors. For this reason, it’s important that people who work indoors get outside periodically, and moreover that we all try to sleep in total darkness. This can have a major impact on melatonin rhythms and can result in improvements in mood, energy, and sleep quality.”

2. Wear Blue Light-Blocking Glasses When the Sun Goes Down

Blue light emitted from laptops, tablets, and other screens can wreak havoc on your sleep cycle and keep you up long after bedtime. This is because researchers believe it may suppress your body’s natural melatonin (14).

To help prevent this, you can wear a pair of blue light-blocking glasses after sunset. These glasses have a special coating to allow you to enjoy your screen time without the melatonin dip.

3. If You Can, Limit Screen Time After 8:00 PM

Blue light isn’t the only reason screen time can harm your sleep. Studies have found that more than two hours of screen time at night can interfere with your body’s natural evening melatonin boost. That means you might find yourself awake and wired way past your bedtime (15).

Try to switch this up by shutting off your tech devices after 8:00 PM. If you can’t cut things off right at 8:00, aim to at least power off your devices an hour before going to bed.

Here are a few other activities you can do instead: Read a book, knit, play a board game, do a Paint By Numbers, practice some gentle yoga or stretching, or have a meaningful conversation with loved ones.

4. Avoid Eating After 7:00PM

Eating before bed is a hotly debated topic, and many researchers agree that curbing overeating before bed is helpful for managing weight and sleep hygiene. Unfortunately, low melatonin creates a negative cycle: when you’re tired, you’re more likely to overeat and gain weight (16).

One way to help combat this and get better sleep is to finish eating 3 to 4 hours before bed. For most people, this falls around 7:00 PM (17).

If you’re truly hungry, don’t feel like you have to deprive yourself! But it’s important to be aware of snacking or overeating late at night because, in addition to causing weight gain, it disrupts your sleep.

Are there any risks to taking melatonin?

Melatonin is considered to be safe for adults to use for the short-term or long-term (21).

That said, most healthcare professionals warn against teens or kids taking melatonin since there’s not enough research to establish safety (22). Melatonin does occasionally cause a few side effects, including nausea, dizziness, and headaches (23). It shouldn’t be taken with some medications, including blood thinners, antidepressants, and blood pressure medicine (24).

Are melatonin hangovers a thing?

Yes! And they’re exactly what they sound like—a groggy, depleted feeling in the morning after taking melatonin (25). But there’s a way to prevent melatonin hangovers. We explain it all in this article.

Should melatonin be used as a sleeping aid for elderly people?

Melatonin levels decrease with age, making melatonin supplements a great option for many elderly patients, especially those with insomnia (26, 27).

How many mg of melatonin is safe?

Experts usually suggest you aim to take the lowest effective dose. For most people, anywhere between 2mg and 10mg can be safe. When you’re first starting out, try not to take more than 5mg until your body adjusts to melatonin.