Depression is a very complicated problem, and there are many factors associated with depression and suboptimal mental health in general.

Within this, one huge factor is circadian rhythm disruption.

Every human has a circadian rhythm, which is roughly a 24-hour cycle that regulates numerous biological functions and dictates the appropriate times to eat, sleep, exercise, and pretty much everything else you need to do.

With this in mind, circadian rhythm disruption happens when people live in an unnatural manner because this disrupts all of the normal signals that the body should be getting. There are specific times that certain things should happen, and when these don’t line up with what’s expected, the end result is suboptimal health.

As you’ll see specifically in this article, disrupted circadian rhythms can have a profound negative influence on mental health, especially depression. Unfortunately, mental health issues themselves, especially depression, can also exacerbate or even cause circadian rhythm disruption, so there is potential for a vicious cycle.

So, to understand a little bit more about the relationship between circadian rhythms and their effect on mental health, and vice versa, let’s take a deeper look at the mechanisms involved. From there, I will list some simple things you can do to restore balance to your circadian rhythm, reduce depression, and enhance your mental health.

TL;DR

If you just want a brief overview of what’s covered below, look no further!

• Circadian rhythms are inherent in every human that help align our bodies with the solar day.
• These rhythms are primarily regulated by light/dark cues, as well as other factors.
• Disruptions in natural ways of life can disrupt circadian rhythms, leading to poor mental health.
• Poor mental health itself (especially depression) can disrupt circadian rhythms too.
• Circadian rhythm disruption and depression are likely in a bidirectional relationship, meaning they both can negatively affect each other.
• Treatment typically involves implementing simple, natural lifestyle components to realign the circadian rhythm:
  • Light exposure during the day
  • Eliminating artificial light at night
  • Exercising during the day
  • Eating during the day and stopping around 3 hours before bed
  • Implementing a consistent sleep/wake schedule
• Managing depression through therapy and other means is also often needed for optimal results.

Now, for those of you who want the specifics, read on below!

Circadian Rhythm Overview

The essential purpose of the circadian rhythm is to align our physiological and behavioral processes with the solar day. That is, certain physiological and behavioral factors are supposed to occur at specific times based on what time of day it is.

It all starts with the suprachiasmatic nucleus (SCN), located in the brain’s hypothalamus. And the SCN is heavily influenced by light/dark cues. Sunlight sends signals to the body (via nerves in the eyes that then travel to specific brain regions) that it is day. And this begins the cascade of processes that are supposed to normally occur throughout the day.

Therefore, the SCN is essentially the pacemaker of the circadian rhythm because it gets the ball rolling for all of the other physiological processes.

So, when in alignment, everything goes smoothly.

• Neurotransmitters and hormones are released at the right times.
• Body temperature fluctuations are congruent with the time of day
• Metabolic and digestive processes are congruent with the time of day
• Sleep-wake cycles are optimized
• And so on.

In this way, circadian rhythms dictate when you should eat, sleep, exercise, relax, and much more. So, doing any of these things at the wrong times can ultimately disrupt this rhythm.

Common Disruptors

Unfortunately, the modern world has many factors that can disrupt the normal timing of circadian rhythms. So, let’s take a look at a few of them.

Light at Night

Light at night disrupts the circadian rhythm because it sends a signal to the body that its daytime, which ultimately leads to ill-timed physiological processes. Primarily, this disrupts the production of melatonin and increases cortisol, which is the opposite of what’s supposed to occur at night. Ultimately, this can disrupt sleep and mental health.

The main disruptors are phones lap-tops, and televisions because they emit blue-light, which is usually only during the day. Even lightbulbs emit some blue light. So, having devices on and the lights on at night all send the wrong signals to the body, negatively affecting sleep as well as mood and behavior.

Lack of Sunlight

All of this is compounded by staying indoors all day, which most people do. Sunlight is vital for serotonin production and regulating the sleep-wake cycle, so a lack of sunlight in the eyes during the day disrupts the sleep-wake cycle even more.

Night Shift Work

Advances in the modern world have also created other problems: night shift work, jet lag, and “social jet lag”. While night shift work can be a blessing for people who need those services, night-shift workers themselves have a risk for mental health issues since their circadian clock is essentially flip-flopped. And this makes it really hard to perform at an optimal level, physically and mentally.

Jet Lag…and Social Jet Lag?

And then there is jet lag, which disrupts circadian rhythms because the body is suddenly exposed to a time of day much different than what it was used to.

But I want to talk more about social jet lag because it happens the most often. Social jet lag is the concept of staying out much later and sleeping in a lot later on the weekends than you do during the week. Although it may seem miniscule, doing this every week can shift the circadian rhythm, making it that much more difficult to adjust back to the work-week times. Maybe that’s one reason why Mondays seem to suck for so many people.

Meal Timing

Another influence on the circadian rhythm is when you eat. The body is designed best to eat when the sun is out and fast when it is dark. So, eating late at night also disrupts the circadian rhythm since this is not the optimal time to eat, and it will cause a cascade of hormones, chemical signals, and other things that aren’t supposed to be occurring at this time. Even the gut microbiota respond best when food is consumed during the day.

Exercise and Movement

Finally, there is exercise and movement. We are supposed to move during the day and rest at night (duh), so any variation in this could also disrupt circadian rhythms.

Firstly, exercising too late at night disrupts circadian rhythms, but staying sedentary throughout the day also does this (yet another reason why sitting all day is terrible for your health.)

And there are other factors too, but these are the main ones.

Consequences

So, what all happens from these factors?

Many things, but primarily:

• Increased cortisol and decreased melatonin production
• HPA-Axis disruption
• Sleep-wake disruptions (such as less slow wave sleep)
• Disruptions in body temperature rhythms (such as increased night-time body temperature)
• Disruptions of serotonin, dopamine, norepinephrine, and other neurotransmitters

Depression Itself as a Circadian Rhythm Disruptor

And what’s scary about all of these factors is that these are the same things seen in depression. In fact, depression itself is a powerful circadian rhythm disruptor because it can lead to all of those factors listed above. When you’re depressed, the following things occur:

• Heightened stress levels
• A lack of motivation to move during the day; thus, a sedentary lifestyle
• Sleeping either too much or not enough, and the sleep is usually not restorative
• Impaired levels of many hormones, neurotransmitters, and other disturbances in overall bodily functions

See the connections now? Many of the features of circadian rhythm disruptions and depression overlap.

Circadian Rhythms Disruption and Depression

So, the main point of all of this so far is that circadian rhythm disruption is associated with the key features of depression, and vice versa.

But the trouble is, what came first? Does circadian rhythm disruption lead to depression or is the reverse true?

More than likely, it is a combination in that they both influence each other, which unfortunately creates a vicious cycle.

Basically, as I said briefly earlier, mood disorders themselves can cause circadian disruption. But factors of the modern world can also exacerbate depression or cause it in susceptible people via circadian rhythm disruption.

No, not everyone who lives in an unnatural manner gets depression, otherwise, we’d all be walking around with it (since nearly everyone lives far from how we’re meant to). But it is a huge risk factor for people susceptible to it.

Also, it is well-known that sleep problems, insomnia, and daytime lethargy/ lack of motivation are often factors in people with depression. This again points to the idea that depressed individuals have an altered circadian rhythm.

Therapeutic Stance

So, what’s one to do about all of this?

Well, it will likely take a multi-faceted treatment approach.

Given the bidirectional nature of these issues, optimal treatment involves both circadian realignment therapy along with therapy specific for depression. Often, the treatments can simultaneously affect both outcomes, which again shows their intricate relationship with each other.

Yet, I can’t treat your depression or other mental health problems specifically through this article alone. That’s why I’ll simply list some things you can start to implement to restore the circadian rhythm aspect of your mental health issues.

Understand that these will likely need to be combined with mental health disorder-specific treatments for optimal results. With that in mind, here are some simple tips to start implementing.

Light Exposure and Timing

So, one very important thing to do is align your light exposure in the most natural way possible. In practice, this means you should be getting exposed to sunlight in the morning and afternoon and limiting (or eliminating) artificial light at night. Aim for at least 5 minutes but ideally 30 minutes (or more) of morning sunlight as soon as you wake up. And get an additional 15 to 30 minutes (or more) in the afternoon.

Bright Light Therapy

Bright light therapy is known to be a powerful antidepressant, not only for seasonal affective disorder (SAD) but depression and other mood disorders in general. This therapy typically involves artificial light therapy boxes, but sunlight is even better because it’s simply what we’re meant to be exposed to. And there are many benefits of getting sunlight. For example, it increases serotonin (and other neurotransmitters) which boosts mood. And serotonin allows more melatonin to be produced at night since the former is converted to the latter in darkness.

Block Artificial Light at Night

The last point about melatonin is why it’s also vital to eliminate artificial light at night. I recommend wearing blue-light blocking glasses after sunset until you go to bed. At the very least, wear them two hours before bed. And you should turn off all electronics ideally one hour before you go to bed, but the earlier the better. Instagram, TV, Facebook…these all have to be eliminated or at least reduced. You can read a book under amber light instead or listen to music. There are many options.

Light/dark cues are the most powerful for SCN regulation and circadian rhythm functioning, which is why I listed these points first. When you get exposed to light and darkness at the optimal times, everything else is more likely to run smoothly.

Sleep/Wake Schedule

The timing of when you wake up and go to sleep is also important. Recall that the circadian rhythm is cyclical and repetitive by nature, so it thrives on routine. This is why you should try to go to sleep and wake up at around the same time every day. This has been proven for a long time to help restore regular sleep patterns. And restoring sleep patterns is absolutely vital since disrupted sleep is one of the hallmarks of depression.

Time-Restricted Eating

You also want to optimize when you eat. A simple way to do this is to just eat when the sun is up and refrain from eating after sunset. Time-restricted feeding is proven to help restore the circadian rhythm. If you don’t want to be that strict, I still recommend eating within two hours of waking up and finishing your last meal at least three hours before bedtime.

Late-night eating is just as bad for mental health as it is for physical health. And you should have a balanced breakfast of protein, fat, and carbohydrates, just like you should at every meal. Unfortunately, appetite disturbances are often seen in depression, so this might have to be separately addressed.

Movement and Exercise

And then there is movement and exercise. I understand that with depression, sometimes it’s hard to move. But you have to start somewhere. If you often feel fatigued and down during the day, simply try to get out and walk a block and back. It all depends on how severe your case is. But make an honest effort to move during the day. You don’t even have to exercise, just move throughout the day.

And if you are able to exercise intensely, I recommend finishing the session at least two hours before bedtime, but morning and afternoon exercise are best. Of course, something is better than nothing. If you’re pretty depressed, you likely aren’t worried about when to exercise intensely, but rather how you can get moving at all in the first place.

A Cure-All?

So, with these points, am I suggesting that depression can be cured simply by changes in light exposure, eating habits, and exercise habits?

Nope! What I’m suggesting (and what is supported heavily by research) is that doing these things offers a way to help realign your circadian rhythm, which in turn solves one piece of the puzzle that is your depression.

Simple, yet Profound

Taking steps towards living a more natural life is always beneficial for improving mental health, and in this article, you’ve seen how just some simple tweaks can help restore your circadian rhythms and potentially help lessen depressive symptoms. If you need further help, whether in doing these things or otherwise managing depression, remember to seek out a qualified mental health care professional. Seeking help as early as possible is vital.

And these points can be combined with many other therapies known for improving depression. Interestingly, a lot of these therapies also may restore circadian rhythm function. Such therapies include electroconvulsive therapy and ketamine administration, along with some antidepressants in general. But that is the topic of another article.

For now, try to take at least one of the steps listed above, implementing more of them over time, and you will be satisfied with the results. After all, it’s how we’re meant to live.

References

• Circadian Rhythm Disruption and Mental Health- https://doi.org/10.1038/s41398-020-0694-0
• Circadian Rhythm, Lifestyle and Health: A Narrative Review- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123576/
• Food Timing, Circadian Rhythm and Chrononutrition: A Systematic Review of Time-Restricted Eating’s Effects on Human Health- https://doi.org/10.3390/nu12123770
• Optimization of Light Exposure and Sleep Schedule for Circadian Rhythm Entrainment- https://doi.org/10.1371/journal.pone.0251478
• Circadian Rhythm as a Therapeutic Target- https://doi.org/10.1038/s41573-020-00109-w
• Is Advancing Circadian Rhythm the Mechanism of Antidepressants? – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6664215/#!po=95.8333
• Light Therapy in Mood Disorders: A Brief History with Physiological Insights- https://doi.org/10.33069/cim.2018.0009
• Circadian Neurons in the Lateral Habenula: Clocking Motivated Behaviors- https://doi.org/10.1016/j.pbb.2017.06.013
• Rhythms of Life: Circadian Disruption and Brain Disorders Across the Lifespan- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6338075/
• Circadian Rhythm and Sleep Disruption: Causes, Metabolic Consequences, and Countermeasures- https://doi.org/10.1210/er.2016-1083
• Systematic Review of Light Exposure Impact on Human Circadian Rhythm-https://doi.org/10.1080/07420528.2018.1527773
• Light Modulation of Human Clocks, Wake and Sleep- https://doi.org/10.3390/clockssleep1010017
• Time-of-Day-Dependent Physiological Responses to Meal and Exercise- https://doi.org/10.3389/fnut.2020.00018
• Level and Timing of Physical Activity During Normal Daily Life in Depressed and Non-Depressed Individuals- https://doi.org/10.1038/s41398-020-00952-w
• Exercise Timing and Circadian Rhythms- https://doi.org/10.1016/j.cophys.2019.04.020