Why are toothaches worse at night?

If you have ever had the unpleasant experience of a real bona fide toothache, you know that it is worse at night. As a matter of fact, one of the first questions your dentist, hygienist or assistant will ask is “Does it keep you up at night?” I’ve had so many patients inquire about why this occurs. Some people speculate that it is because people are busy during the day, but at night when they slow down, they happen to notice the pain more. This theory may be true to a certain extent, but the truth is your tooth seems to hurt worse at night, because it does hurt worse at night. To better understand how and what exactly happens to cause a toothache to be worse at night, I want to explain a couple of hormones that play a vital role in inflammation.

Cortisol

Most people think of cortisol as a stress hormone. It certainly is released during high stress situations, but in addition it plays a role in regulating glucose levels, metabolism, and blood pressure, it assists with memory formation, and helps reduce inflammation.[1] That last function is the one that is important when we are experiencing a toothache. An interesting side note that has nothing to do with dentistry, cortisol has been shown to play a role in attracting a romantic partner.[2] Obviously this is an important hormone.

Adrenaline

Another hormone that plays into this scenario is adrenaline. Adrenaline is known to induce fight or flight response in stressful situations. Adrenaline dilates air ways to provide more oxygen to muscles, it also constricts blood vessels to redirect blood flow to larger muscle groups. Adrenaline plays a role in reducing the bodies ability to feel pain.[3]

Prostaglandins

Prostaglandins are important hormones that help maintain homeostasis and mediates the inflammatory response, among other important tasks. Prostaglandins contribute to the signs and symptoms of acute inflammation. These include redness, heat, swelling and pain. Prostaglandins mediate arterial dilation, increased microvascular permeability which contributes to in increased blood flow to the inflamed tissues resulting in swelling and edema. Prostaglandins communicate directly with peripheral sensory neurons and in central sites within the spinal cord and brain resulting in pain.[4]

Histamine

It is well documented that histamine plays a major role in the inflammation response. Histamine is an inflammatory mediator which intensifies and prolongs the inflammatory response. Histamine is also responsible for regulating microglial activation in the nervous system which leads to the production of proinflammatory cytokines.[5]

Melatonin

Melatonin is the hormone most associated with the sleep cycle. Melatonin is also an immune modulator that has pro and anti-inflammatory properties and has been shown to enhance the resistance to pathogens.[6] Melatonin reduces tissue destruction during the inflammatory response. A study conducted to evaluate melatonin’s relation to the immune system and inflammation states, “There is indirect evidence that melatonin inhibits the production of adhesion molecules that promote the sticking of leukocytes to endothelial cells. By this means melatonin attenuates transendothelial cell migration and edema, which contribute to tissue damage.”[7]

Before I bring this altogether, I would like to preface it by saying I am presenting this in a very simplified manner. There are many more hormones and cells that play a role in the inflammation process. I want this to be easy to understand for everyone. Many people have limited knowledge about anatomy and physiology and for that purpose I have simplified the process and mechanism.

So, what exactly happens when you go to bed at night to cause your tooth to begin to throb, and make the pain almost unbearable? Well, the very definition of a tooth ache is “acute inflammation”. When you have acute inflammation, your body initiates your immune response. One of the first things that happens is the release of prostaglandins. Prostaglandins initiate inflammation which tries to remove the offending pathogen. Remember this, it will be important later.

When it gets dark our body releases melatonin, this decreases the production of cortisol and adrenaline. These two hormones are responsible for keeping us awake during the day, so reduced production promotes sleep. When you have acute inflammation, such as a toothache this is a double-edged sword. Melatonin helps to promote healing but shuts down the very hormones that reduce inflammation and suppress pain. Resulting in increased pain and sleep loss. All that sleep loss will make you feel terrible, but you won’t be able to catch up on it until you have your tooth treated, because the inflammation process is signaling histamines to be released. Histamine blocks melatonin, and around and around we go.[8]

If you are lucky, you will only have to suffer through one night of this. However, if you’re not that lucky person that takes heed and calls the dentists right away, this cycle will continue until you see a dentist or find yourself in the hospital. To add insult to injury, the more sleep you lose the more prostaglandins are released. This increases spontaneous pain.[9]

Toothaches can strike anyone, of course seeing a dentist regularly will certainly reduce the risk. If you find yourself feeling throbbing pain, sensitivity to hot or cold, or pain upon chewing please do not wait until 4:00 on a Friday afternoon to call your dentists. If you do, you might find yourself on the toothache/sleep loss merry-go-round through the weekend. If you are a regular victim of Murphy’s law, and you start having pain on a Friday night or Saturday, the best thing for toothache pain has been proven to be NSAIDs. COX enzymes produce prostaglandins, NSAIDs block COX enzymes and reduce the production of prostaglandins which reduces inflammation and pain.

I would like to add inflammation is not a bad thing, it is necessary as part of the healing process. Inflammation gets a bad rap; however, it is chronic inflammation that leads to other systemic issues. I hope anyone reading this never suffers from a toothache, but if you do, I hope this information helps you understand the need to contact your dentists ASAP and how to treat the pain until you can be seen.

Resources

1. Hormone Health Network. What is Cortisol? Retrieved from https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/cortisol

2. Van der Meij, L, Demetriou A, Tulin M, Mendez I, Dekker P, Pronk T. Hormones in Speed-dating: The Role of Testosterone and Cortisol in Attraction. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/31348926

3. Hormone Health Network. What is Adrenaline? Retrieved from https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/adrenaline

4. Emanuela Ricciotti, PhD and Garrett A. FitzGerald, MD. Prostaglandins and Inflammation. Arterioscler Thromb Vasc Biol. 2011 May; 31(5): 986-1000. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3081099/

5. Anna Cláudia Calvielli Castelo Branco, Fábio Seiti Yamada Yoshikawa, Anna Julia Pietrobon, and Maria Notomi Sato, “Role of Histamine in Modulating the Immune Response and Inflammation,” Mediators of Inflammation, vol. 2018, Article ID 9524075, 10 pages, 2018. Retrieved from https://www.hindawi.com/journals/mi/2018/9524075/

6. Hardeland, R. Melatonin and inflammation—Story of a double‐edged blade. J. Pineal Res. 2018; 65:e12525. Retrieved from https://onlinelibrary.wiley.com/doi/full/10.1111/jpi.12525

7. Reiter RJ, Calvo JR, Karbownik M, Qi W, Tan DX. Melatonin and its Relation to the Immune System and Inflammation. Ann N Y Acad Sci. 2009; 917: 376-86. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/11268363

8. Thomas E Scammell, Alexander C Jackson, Nicholas P Franks, William Wisden, Yves Dauvilliers, Histamine: neural circuits and new medications, Sleep, Volume 42, Issue 1, January 2019, zsy183. Retrieved from https://academic.oup.com/sleep/article/42/1/zsy183/5099478

9. Monika Haack, PhD, Erin Lee, MPH, Daniel Cohen, MD, and Janet M. Mullington PhD. Activation of the Prostaglandin System in Response to Sleep Loss in Healthy Humans: Potential Mediator of Increased Spontaneous Pain. Pain. 2009 Dep; 145(1-2): 136-141. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2737342/