Melatonin and Sleep Part 1: The Basics
Chronic sleep deprivation can lead to decreased productivity, mood alterations, and even physical health issues. So, it is not surprising to see those suffering from sleep issues trying various strategies to achieve restful and lasting sleep. One popular option is to take melatonin supplements to help fall asleep. Many take melatonin due to a number of different sleep concerns, such as jet lag, circadian rhythm issues, shift-work, as well as insomnia.
In the first part of this two-part blog, I will delve into the science behind melatonin, how it affects sleep, and the potential side-effects and precautions. In the second part of this blog, I will focus further on the relationship and effectiveness of melatonin particularly with insomnia.
The Basics of Melatonin
Melatonin is a hormone produced by the pineal gland in the brain that is responsible for regulating the sleep-wake cycle. There are also extra-pineal sites of melatonin production, such as the retina and the gut. This hormone is produced and regulated in response to light and darkness (as per information received from your retinas), with levels rising in the evening by about 10 times to promote drowsiness and falling in the morning to promote wakefulness. Pineal melatonin levels begin increasing in the late evening, reaching the maximum in the early hours between 2:00 and 4:00 a.m., followed by a slow decline to a lower daytime level that is barely detectable.
The production and secretion of melatonin is controlled by the circadian rhythm, which is the body's internal biological clock that follows a 24-hour cycle. There are also seasonal rhythms to the production of melatonin, with higher levels in fall and winter (longer dark hours) and lower levels during spring and summer (longer day time hours). This hormonal regulation of the sleep-wake cycle is a critical component of healthy sleep patterns.
Age: The normal production of melatonin can vary with age and it typically decreases as we get older. This decline is due to the pineal gland not storing and releasing melatonin as effectively due to calcification over time. In addition, changes in vision or eye conditions, such as cataracts, can impact the amount of light the eyes receive. The following is an overview of the typical amount of melatonin produced by age:
0-3 months: little to none
1-3 years: reaches the highest concentration
Rest of childhood: levels drop by 80%
Adults: additional drop of 10%
Older adults: 20% of that of a young adult level
Source: T. B. Grivas, O. D. Savvidou (2007). Melatonin the "light of night" in human biology and adolescent idiopathic scoliosis.Scoliosis 2:6. DOI: 10.1186/1748-7161-2-6
Sex: After puberty females generally have higher levels of melatonin than males. Melatonin has also been demonstrated to interact with female hormones. It appears that menstruation modifies such levels, while oral contraceptives have been found to increase nighttime melatonin levels due to inhibiting catalyzing enzymes in the liver.
Diet: There is evidence that diet can influence the synthesis or the concentration of melatonin (to a lesser degree than light). Lowering one’s caloric intake has been shown to reduce the secretion of melatonin at night. Short-term fasting of 2-7 days, resulting in limited intake of energy, was shown to reduce melatonin concentration in the blood by about 20%, whereas glucose supplementation returns the melatonin production back to normal.
Nutritional factors can also modify melatonin levels, both by the mechanism of containing melatonin or by stimulating its production. Melatonin is synthesized from tryptophan, an essential dietary amino acid. If the intake of tryptophan is severely restricted, the synthesis of melatonin is also significantly reduced. There are several foods, especially plants, that contain melatonin and its precursor tryptophan. A few examples include tomatoes, walnuts, rice, olives, barley, and milk.
Medical conditions: Several medical conditions can impact the production and level of melatonin. A decrease in this hormone’s levels is seen in neurodegenerative disorders, such as Alzheimer's disease and other types of dementias, which can be attributed to tissue degeneration. However, there are other neurological and metabolic conditions that can also reduce melatonin production independently of tissue damage. These include diabetes type 2 and general insulin resistance, migraine and other forms of severe pain, as well as certain types of cancers (Endometrial cancer, Nonsmall cell lung cancer).
Potential Side Effects and Precautions
While melatonin is generally considered safe for most, it is important to be aware of potential issues and how its use may impact you specifically. It is imperative to consult with a healthcare provider before starting melatonin supplementation, especially for those with existing medical conditions and/or taking medication:
Side-effects: A few common side-effects identified are headaches, nausea, dizziness, feeling irritable or restless, allergic reaction, dry mouth, dry or itchy skin, pains in your arms or legs, strange dreams or nightmares, or night sweats.
Pregnancy & Breastfeeding: Melatonin passes into breast milk in small amounts. There are not enough research to understand its safety, and therefore avoiding this hormone is generally recommended.
Drug Interactions: Melatonin may interact with certain medications, including antidepressants, blood thinners, birth control pills, insomnia medication, anticonvulsants, Diabetes medication, immunosuppressants, and OCD medication.
Long-term Use: Long-term use of melatonin supplements is not well understood, and more research is needed to determine its safety and efficacy over time. Some experts believe that long-term use can result in a reduction of the body's natural production of melatonin. However, more research is required to better understand the impact.
Dosage: It is also important to be mindful of the amount that is optimal for your needs vs. the dosage that you are consuming. While investigating the levels of melatonin in obtaining a goodnight’s sleep in adults over 50, an MIT study found the dose of 0.3 milligrams of melatonin to be sufficient. However, they noted that the typical over-the-counter dosage is about 10 times this amount. The researcher in this study cautioned that the higher dosage can lead to side-effects such as hypothermia, as well as the “hangover” effect experienced the next day.
Regulations: There is a lot to be desired when it comes to supplement reliability. A 2017 study by University of Guelph found that melatonin content in supplements ranged from 83% less to 478% more than the concentration declared on the product label. It also found shocking lot-to-lot variability—melatonin levels varied by as much as 465% when comparing different batches of the same product from the same manufacturer, as well as 70% of the labels had less than 10% of the melatonin concentration claimed. In addition, 26% were found to contain serotonin (a neurotransmitter), which raises concerns as consuming unknown levels can negatively impact the body, as well as those taking mood disorder medications.
In conclusion, melatonin is a fascinating hormone that plays a crucial role in regulating our sleep-wake cycle. Understanding its effects and how to use it effectively can be the key to unlocking a good night's sleep for some. However, it's important to approach melatonin supplementation with caution and to always consult with a healthcare provider before starting any new supplement. Whether you're looking to boost your body's natural production of melatonin or supplementing with a synthetic form, a thoughtful and informed approach is the best way to ensure a safe and effective outcome. It is also worth looking into other effective treatment options for your sleep issues that may be a good fit for you. Remember, a good night's sleep is essential for physical, mental, and emotional health, so take the time to prioritize it in your life. With the right tools, you can turn the dreams of a restful sleep into a sweet reality.