New Science Shows How Lack of Melatonin Makes You Hungry and Fat

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A new study shows that not having enough melatonin, your sleep hormone, messes with your hunger and satiety signals and leads to weight gain.[ref url=””]

Melatonin is your main sleep hormone in a cocktail of hormones that your body releases to get you to sleep. Your pineal gland in your brain secretes melatonin in response to darkness. So, to find out what happens when you don’t have melatonin, researchers removed the pineal gland in rats.

One group of rats received melatonin in their drinking water during the dark hours of a 24-hour period, and the other group didn’t have melatonin at all. The researchers found that the rats that lacked melatonin:

Showed reduced leptin (satiety hormone) sensitivity

  • Ate more
  • Weighed more
  • Had more body fat
  • Ate substantially more than the no-melatonin group after both groups fasted for 24 hours

Another study linked blue light exposure at night with weight gain in women, which could be related to melatonin production.[ref url=”″] When you’re exposed to blue wavelengths, your body thinks it’s daytime and won’t release melatonin.

Do you make enough melatonin?

Unless your brain surgeon told you otherwise, you have a working pineal gland. So, you must be making melatonin, right?

Maybe. With all of the artificial light that is part of modern society, your pineal gland may be getting mixed signals. Detecting certain wavelengths, like blue light from devices or from fluorescent lights at the airport after a late flight, makes your pineal gland think it’s day and delays melatonin release. After a few nights of that, it throws off your natural body clock.

The obvious consequence? You’re awake when you want to sleep, then tired when you want to be awake. The effects on your food intake are less immediate, so you might not put two and two together. This study points to a possible cause-and-effect relationship.

Weight loss experts have become more and more aware of the effects of sleep on your bodyfat, and have been recommending good sleep as part of your weight loss strategy. Is it sleep, or is it melatonin? Sleep and melatonin are inextricably linked for sure, but this study could point to melatonin as a key player in weight and metabolism.

What I do to regulate my melatonin

Take a high-qualtiy melatonin supplement

If you do overnight shift work or work into the night, a melatonin supplement is absolutely crucial. With artificial light, on top of active and rest times that aren’t in line with your body clock, your pineal gland is likely releasing melatonin when you want to be awake and holding back when you’re ready to sleep.

A high-quality melatonin supplement can give you the support you need so that you can do what you need to do during the day and night, and possibly avoid negative effects on your appetite and weight. Here’s how to supplement without the “melatonin hangover” and other side effects. I like Sleep Mode because it has just the right amount of plant-based melatonin, and it’s not habit-forming.

Control light exposure

When I’m around junk light during the day, I’ll wear my amber TrueDark Daylights. Closer to bedtime, I’ll switch to the red Twilights, which completely filter out the wavelengths that keep my pineal gland from doing its thing.

Then, when it’s time to go to bed, I make sure there’s no light coming into the room. That’s a non-negotiable for me — my bedroom has to be in total darkness. From slivers of light from in between curtains, to little dots of green light from chargers … it all has to go. I’ll go as far as taping the curtains and taping TrueDark Junk Light Dots on any and every light source in the room.

Turn off wireless routers and devices

Your wireless router emits electromagnetic fields (EMFs), which could disrupt your sleep. You don’t need internet connectivity at night, so you can simply unplug it. You can also switch all of your devices to airplane mode so they do not emit EMFs.

Get more ways to sleep harder and better

Reading glasses on closed laptopFor more information about sleep hormones and better sleep, check out these Bulletproof Radio episodes where I dig deep into sleep science with the leading sleep experts.

Sleep is the Boss of You – Matthew Walker, Ph.D., Episode #616 

Sleep Need & Sleep Age – Get Yours – Dan Gartenberg, Ph.D. Episode #583 

Eating Affects Your Sleep (and Vice Versa) – Satchin Panda, Episode #560 

The Neuroscience of Sleep Hacking – Dan Levendowski, Episode #520 





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