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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Sleep, Dog Cancer, and Melatonin

Updated: April 5th, 2021


Melatonin and dog cancer … why this powerful natural hormone produced inside your dog’s brain can help fight cancer. Inexpensively!

What do melatonin, dog cancer, and sleep have to do with each other? I’d like to go out on a limb. Call me crazy. Open a new window on your monitor. But I’ve discovered something about dog cancer:

The closer a dog’s lifestyle is to how it was in nature, the lower the probability of getting malignant tumors.

Now, it’s true that if you read the Meet Dr. Dressler bio you will see that my parents were hippies, more or less. Over the years I have been known to eat granola if it’s in the house. I did own a pair of Birkenstocks when I was a freshman in college.  Okay, fine.

Listen to this episode of Dog Cancer Answers to find out more about how to use melatonin to fight dog cancer. 

But even with that background, as a scientist, I cannot deny the truth of this statement. The more I learn about cancer, the more evidence I uncover for it:

The closer a dog’s lifestyle is to how it was in nature, the lower the probability of getting malignant tumors.

Dr. Dressler’s best advice for you, if your dog has cancer.

Notice that I’m not saying that a natural lifestyle will prevent all tumors. I’m also not saying that a natural lifestyle will cure all tumors.

I’m just saying it lowers the risk of them. Get it? No absolutes here.

But here’s an example of how a natural lifestyle can lower the risk of cancer: deep sleep, in total darkness, during actual night hours, fights cancer.

No, don’t laugh!  This is real.  Let me explain.

Night Shifts Increase Risk of Cancer

Melatonin, dog cancer — the evidence comes from human medicine, as is so often the case.

Turns out that female nurses who stay up to work during the night shift have a very real increased risk of breast cancer.  Sleep has something to do with it.

When our dogs (or in the cases study, nurses) are resting, a hormone called melatonin is released by a gland in the brain called the pineal. The deeper the sleep, the more melatonin is produced.

Melatonin production peaks at about 1:30 AM, when the night is at its darkest and our [dog’s] sleep is deepest.

Lots of us have heard of melatonin as a supplement that can help with insomnia or jet lag.  That’s a good use for it, definitely, although it has been found that melatonin has many more effects in the body than just making us drowsy.

Here’s the rub: melatonin is a major cancer fighter.

Melatonin, Dog Cancer?

This little tidbit of information is almost totally overlooked in conventional veterinary cancer care.  Gobs of evidence that melatonin helps fight cancer, yet, nobody is talking.

Maybe because melatonin is not patentable (difficult for big pharma to farm a cash cow when anyone can get it cheap…).

I’d like to spend some time talking about this stuff in the next post.  First, how to increase your dog’s melatonin levels without spending a dime.  Next, I’ll go into some detail about what it does in the body that has bearing on dog cancer. We are talking solid firepower folks. Whether your dog has lymphosarcoma, hemangiosarcoma, mast cell tumor, bone cancer or whatever, you’ll want to know about it.

Stay tuned!

Best to all,

Dr Dressler

PS: Note from the editor — to read more about melatonin and how to use it to treat your dog’s cancer, please read the Cancer Causes chapter of The Dog Cancer Survival Guide. Also read the chapter on Anti-Metastatic Supplements!


Leave a Comment

  1. Ah on January 3, 2023 at 2:14 pm

    My dog has lymphoma and is almost at her end fighting it. I’ll try anything to help her as the vet said she will need surgery and chemo with only an extended life of a few months (she is 10). She is still trying so hard to be involved with my family and wagging her tail but the lumps are there, her lack of appetite and pain. How much can I give her to maybe help her be more comfortable, maybe even help fight this? She is on Prednisone but it isn’t helping much anymore

  2. Adam Halcomb on January 13, 2022 at 2:37 pm

    I have a dog that has tumors in his neck, do you think giving him melatonin can help? He’s had way to many surgeries for me to consider this again. I’m struggling!

    • Molly Jacobson on January 15, 2022 at 12:46 pm

      Melatonin may help, but as Dr. Dressler points out in the podcast, it often makes dogs really groggy and disoriented, which is why he suggests focusing on a dark sleeping environment, instead.

  3. Judith Rosen on December 2, 2016 at 6:58 pm

    Hi Dr. Dressler, All the research I’ve done into this supports your conclusions. You’re right: total darkness at night can prevent and fight cancer. It’s not just sleep we need; it’s “dark”. Artificial light at night shuts down circulating melatonin production by the pineal gland, and melatonin turns out to play many important roles in the body. I found your blog as I was looking for information about whether this is as true as it is for humans and lab rats. It would appear to be so, given what you’ve said.

    What current research to day suggests is that supplemental melatonin can both help the body tolerate chemo and radiation far better, but it also kills cancer cells through several different modes of action. In one study I saw, melatonin supplementation was shown to help the rat’s bodies actually kill cancer grafts in the entire group, even though they were exposed to dim light at night (which, otherwise, hastened tumor growth at a rate 150% faster than rats in the groups that experienced total darkness for 12 hours every 24. So, supplemental melatonin was able to eradicate cancer in an entire group of lab rats, despite exposure to dim light at night.

    There have been no reported dangerous side effects that I have seen in the medical science literature, even with over 100 mg doses of melatonin, which is astonishing– because the estimated human adult production is around 5 to 8 mg per night and it has so many functions in the body. I take 20 mg every night, at bedtime and have been doing so for nearly a decade. It has cured me of insomnia which was the bane of my 30’s. (Parenthood is bad for sleep!) So far, I am (knock wood) cancer free at the age of 56. While there is no way to know whether taking melatonin at bedtime is responsible for that, it is clear that it’s not harming me!

    The way I found your blog was that I was searching on the melatonin situation with canines because my daughter’s dog was just diagnosed with bone cancer and we are planning to try and help her using around-the-clock melatonin supplementation. I suspected that since dogs aren’t nocturnal, they would have the same melatonin response to light that our bodies do. By the way, the sensors in human eyes that are hooked up (indirectly) to the pineal gland rather than to our visual cortex were only discovered in the 1970’s. I found that interesting.

    Anyway… thank you for covering this on your blog!

    All the best,
    Judith Rosen

  4. Anonymous on June 14, 2009 at 11:20 am

    My dog was just diagnosed with Cushings. He pants alot and doesn’t sleep, which me I don’t sleep. I heard giving a dog the vitamin Melatonin can help. Is this true and is it safe?

  5. Lori Michaelson on October 3, 2008 at 11:49 am

    Besides sleep and melatonin there is a reason why dogs (Canis lupus familiaris) have CANINES — to rip and shred apart their prey for eating in nature. So obviously this is from MEAT (and fats) from cows to bison!

    This may have been covered in another thread but, having said that, wouldn’t that be a reason to have your dog on a high protein diet or give them meat as often as possible? Although, unless you get the meat without all the extras they put in it these days… it is not totally natural.

    Sorry if this has been covered before!


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