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Melatonin and Thyroid Health

Published July 7 2014

Melatonin is a hormone which is secreted by the pineal gland. Its primary function is to help regulate the body’s circadian rhythm. I’ve discussed the circadian rhythm in the past with the hormone cortisol, as this hormone should be at the highest levels when we first wake up, and at the lowest levels at night. With melatonin the opposite is true, as when it is dark your body normally produces more melatonin, and when it is light the production of melatonin decreases. And of course there are factors which can interfere with the normal melatonin cycles.

Many people reading this are familiar with the benefits melatonin has with regards to sleep. Low levels of melatonin at night can cause insomnia, and as a result, taking melatonin can help people to sleep better. However, melatonin has other roles besides helping us to get a good night’s sleep. Melatonin is also a powerful antioxidant, and so it is important for the health of the immune system. In fact, having healthy melatonin levels can potentially help to prevent the development of certain types of cancers (1) [1] (2) [2].

A recent article in the New York Daily News discussed how taking melatonin supplements can help to improve bone density (3) [3]. The study found that melatonin might inhibit the activity of osteoclasts, which break down bone. Apparently more research is necessary to determine whether supplementing with melatonin actually reverses the breakdown of bone, or if it just prevents this.

Melatonin also might help people with gastroesophageal reflux disease (GERD). It is estimated that approximately one-third of people in the United States have GERD. And to no surprise, prescription drugs are commonly given to help relieve the symptoms. In most cases proton pump inhibitors reduce the production of gastric acid. But just like any other drug, this can have harsh consequences. However, having low levels of melatonin can lead to GERD as well (4) [4]. And so if someone has acid reflux, they might want to clean up their diet and try taking 3mg of melatonin at night before going to bed for a few weeks and see if this helps.

There is also a relationship between melatonin and the hormones estrogen and progesterone. A few studies have shown that melatonin has antiestrogenic mechanisms which may play a role in the prevention and treatment of breast cancer (5) [5] (6) [6]. Melatonin stimulates the secretion of progesterone (7) [7]. In fact, both melatonin and progesterone seem to have a reciprocal relationship, as melatonin increases in the luteal phase (8) [8], which is characterized by an increased production of progesterone. Progesterone can help to prevent sleep disturbances by modulating melatonin, along with growth hormone and TSH (9) [9].

What Causes Low Melatonin Levels?

Although it’s great that there are melatonin supplements available to take whenever necessary, the goal should be to determine what is causing a disruption of the normal melatonin cycles. In other words, why do many people have low melatonin levels at night when the opposite should be true? Well, there are a few different factors which can disrupt the circadian rhythm and cause low melatonin levels at night.

Perhaps one of the biggest culprits is all of the electronic devices surrounding us. They can decrease melatonin production in numerous ways. First of all, many people will watch television or use their computer right up until the point they go to bed. So when our body should normally secrete melatonin at night, watching television or going on the computer might delay the process. The same could be true with electronic reading devices, as many people will read these right before going to bed at night. So if you have problems sleeping at night, or a condition such as GERD, then you might want to try ditching the electronic devices at least one hour before going to bed.

EMFs are a big factor, as these can potentially interfere with melatonin production. Ann Louise Gittleman discusses this in her wonderful book “Zapped”. She talked about how even low levels of EMFs can depress the body’s production of melatonin. If you have an electronic device such as a television, DVR, computer, wireless router, or any other electronic gadget, you need to unplug it at night. Just turning it off isn’t sufficient. And of course this also includes your cell phone, which many people use as an alarm clock.

Another factor which can interfere with melatonin production is not having the room completely dark when sleeping. Obviously you don’t want to have the television or computer on during this time, but even the digital display from an alarm clock, or the display on a DVR might interfere with melatonin production. I realize this might sound extreme, but if someone is having problems with sleep then often times extreme measures are required. And so I would make sure the room is completely dark.

The Precursors of Melatonin

One also needs to be aware of the precursors of melatonin, as if these are deficient then this will lead to low melatonin levels. Serotonin is a precursor to melatonin. As a result, if someone has depressed levels of this neurotransmitter, then they are likely to have low melatonin. So if someone has low melatonin levels, this very well might be due to low serotonin levels. But why would someone have low serotonin levels? Well, you also need to consider the precursors of serotonin. This includes the amino acid tryptophan, but also requires certain nutrients such as iron, magnesium, folic acid, and vitamin B12. If someone has one or more of these nutrient deficiencies, this in turn can cause low serotonin, which in turn can lead to low melatonin.

So let’s look at an example of someone who has difficulty sleeping, and for a different reason they obtain an iron panel which shows a low ferritin and iron saturation. They might not link the iron deficiency to the low melatonin levels, and thus the problems with sleep, but the low iron levels might be responsible for the decreased production of melatonin. Similarly, if someone is deficient in magnesium this can also be the culprit, and is a reason why sometimes taking magnesium at night will help someone to sleep better. On the other hand, if someone has sufficient levels of magnesium but has a methylation problem which is causing a folate and/or vitamin B12 deficiency, then in this situation taking magnesium probably won’t help with the sleep, but having the person supplement with natural folate and/or vitamin B12 while addressing the methylation issue would be warranted.

Speaking of methylation, when serotonin is converted to melatonin, methyl donors are required for this conversion process as well. As a result, if someone has low melatonin levels due to problems with methylation, while taking melatonin might help, it’s also important to focus on the methylation problem. Keep in mind that I’m not opposed to people taking melatonin, as there are times when I will recommend melatonin supplementation to my patients. But at the same time it’s also important to figure out why someone has low melatonin levels.

Testing For a Melatonin Deficiency

Melatonin can be tested through the saliva, urine, and blood. However, there are limitations to these types of testing (10) [10]. Meridian Valley labs offers a 24-hour test for measuring melatonin levels. Genova Diagnostics offers a comprehensive melatonin profile, which analyzes three saliva samples taken at morning, noon, and midnight.

Melatonin and Thyroid Health

So how does melatonin relate to thyroid health? As I mentioned earlier, melatonin is secreted by the pineal gland, and this also is a source of thytrophin-releasing hormone (TRH), which in turn causes the body to release TSH, which signals for the secretion of thyroid hormone. But melatonin may also have a direct effect on thyroid hormone production by stimulating TSH (11) [11]. One study involving perimenopausal and menopausal women showed that taking 3mg of melatonin for three to six months can increase the levels of thyroid hormone (12) [12]. So although most cases of hypothyroidism are caused by Hashimoto’s Thyroiditis, one also should consider the impact that melatonin has on thyroid health.

Because melatonin might increase thyroid hormone production, people with hyperthyroidism and Graves’ Disease might wonder whether they should avoid supplementing with melatonin. If someone with a hyperthyroid condition has a deficiency in melatonin, then taking a melatonin supplement probably won’t cause any problems. On the other hand, if someone doesn’t have a melatonin deficiency but chooses to take melatonin supplements then it might increase the hyperthyroid symptoms. Just remember what I said earlier about wanting to address the cause of the melatonin deficiency, as even if someone has a hypothyroid condition they don’t want to rely on melatonin supplements for a prolonged period of time.

Can Melatonin Cause or Worsen an Autoimmune Condition?

Some people are concerned that taking melatonin can potentially worsen an autoimmune condition, and thus perhaps should be avoided by those people with Graves’ Disease and Hashimoto’s Thyroiditis. The main reason for this concern is due to a clinical trial in 2007 involving patients with rheumatoid arthritis (13) [13], which showed that taking 10mg of melatonin daily increased the concentration of some inflammatory indicators, such as erythrocyte sedimentation rate (ESR). However, the same study showed that melatonin didn’t cause an increase in proinflammatory cytokines. In addition, in 1997 a patient developed autoimmune hepatitis after taking melatonin for the treatment of insomnia (14) [14]. Of course there was no way to prove that the melatonin supplement is what triggered the autoimmune condition. A recent review article showed that with most autoimmune diseases, melatonin actually was of benefit (15) [15]. The author concluded by suggesting that endogenous melatonin can be important in preventing the development of autoimmune disease, and that taking melatonin supplements might be beneficial in the treatment of autoimmune conditions. Although I don’t give melatonin to a lot of my patients, I have had some of my patients with Graves’ Disease and Hashimoto’s Thyroiditis supplement with it, and I don’t recall a situation where it exacerbated someone’s condition.

So hopefully you now have a better understanding of the role melatonin plays. Although a deficiency of melatonin can cause insomnia, it can lead to other health conditions as well. Low melatonin levels can have a negative effect on the health of the immune system, can result in decreased bone density, might cause GERD, and might lead to a decrease in thyroid hormone. There is also a relationship between melatonin and the hormones estrogen and progesterone. Although supplementing with melatonin might be helpful at times, the ultimate goal should be to determine what is causing the melatonin deficiency.