272018Mar
Doctor Articles: Circadian Rhythms

Doctor Articles: Circadian Rhythms

By: David Benhayon, MD, PhD, IRMC Physician Group Neuropsychiatric Associates

Human beings are creatures of habit, and many of these habits are biologically programmed into our brains. Most everything we do is in response to the environment around us, and though we rarely stop to consider this, one of the major ways in which we are affected is by the 24 hour day-night cycle. Earth rotates on 24-hour cycles, and it is not coincidence that humans also operate on this pattern. This is a result of circadian rhythms. Circadian rhythms are the ways in which we coordinate our bodily processes to be on this same 24-hour day-night schedule as the world around us. The most common rhythm is sleep and wake, and the majority of us are entrained to go to sleep during the night and wake in the morning. However, numerous other bodily functions fluctuate on a 24-hour cycle, including temperature, hormone secretion, blood pressure, hunger, even motor coordination. Circadian rhythms are dictated by a small region of the brain called the suprachiasmatic nucleus (SCN), and this tiny area of the brain is known as the ‘master pacemaker.’ Light from the surrounding environment is detected by certain cells in the retina and these cells then signal to the pacemaker, which then tells our body when to be tired or when to wake. In addition, the absence of light in our environment causes the pineal gland, another tiny region of our brain, to secrete a hormone called melatonin. Melatonin may be thought of as ‘the anti-light hormone’ and has two separate functions. Melatonin can make people tired, but it can also help coordinate circadian rhythms properly. It is a powerful tool with which individuals can improve their sleep.

The job of linking our circadian rhythms to day-night cycles was relatively simple throughout much of human history, as we depended upon sunlight and darkness to do most of the signaling to our retina and then the SCN. However about 120 years ago this all changed with the advent of the electric light by Westinghouse (or Edison, depending upon who you believe). Now for the first time, people could easily be awake and working at any hour. Though poorly understood at the time, artificial light has the ability to disrupt our circadian system, thereby altering our basic rhythms. As technology has advanced, our exposure to lights is now far more prevalent. Moreover, lights in the form of television, computer monitors, and telephones have become a major part of our days and nights. There are certain shades of blue light that have been shown to inhibit melatonin secretion, and this is disrupting sleep patterns more than ever before. As monitors become more pervasive and powerful, this problem will only get worse.

Melatonin is a supplement that is not regulated by the Food and Drug Administration (FDA), and it is available over the counter in numerous forms (tablet, gummy, capsule, liquid). It is generally thought to be quite safe, and many people find it very beneficial. On occasion, it can cause mild headache, nausea, dizziness, or even nightmares, and rarely there are drug interactions reported. Generally, melatonin comes in multiple dosages, but 3 mg is usually a good starting point. As stated above, it can have two very different functions, as it can help people fall asleep, but it can also help people to get back onto a normal sleep schedule depending upon when it is taken. Most research suggests that melatonin is most beneficial when taken 1-2 hours before desired bedtime. This is most effective when combined with good ‘sleep hygiene,’ a term used to describe proper sleep habits. These include trying to do relaxing activities before bed, limiting naps during the day, limiting caffeine intake, and removing distracting things from the bedroom (such as televisions, phones, music).

The importance of getting good sleep cannot be overstated. In our busy lives, we have countless responsibilities, however study after study illustrates the importance of getting good sleep at night. Poor sleep has been correlated with an array of things ranging from increased motor vehicle accidents to heart disease to substance abuse. Unfortunately, disruption of circadian rhythms over extended periods of time has also been shown to result in significantly worsened mental and physical health. For those individuals who do work nights, it is usually better to work several nights in a row rather than go back and forth. In addition, physical exercise is also thought to be beneficial in making people tired and is highly recommended. It is often easier to go from daylight shifts to evenings and then to night shifts rather than trying to go in the opposite direction. To summarize, getting better sleep is an often neglected way to make major improvements on physical and mental health, and a better understanding of circadian rhythms could hopefully help us make positive changes.


David Benhayon, MD, PhD, is a board-certified child and adolescent psychiatrist from Knoxville, TN. He currently practices medicine with IRMC Physician Group Neuropsychiatric Associates. To schedule an appointment with Dr. Benhayon, call 888-452-IRMC (4762).

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