Do you start feeling lethargic once the weather starts getting colder? Maybe you’re less enthusiastic about hanging out with your friends, or taking part in activities that you usually love? And just like magic, your zest for life comes back as soon as it’s springtime? You might be suffering from seasonal affective disorder (SAD), or the winter blues.
During the winter months, it’s natural for life to slow down a bit. Even for perfectly healthy people that don’t have seasonal depression, the energy levels tend to be lower than spring and summer months. However, for people suffering from SAD, the problem is more severe than a simple case of sluggishness.
Here, we’ll discuss what seasonal affective disorder is, some of its potential causes, and explore some natural remedies like light therapy, behavior counseling, vitamin D supplements, and more.
What is Seasonal Affective Disorder (SAD)?
SAD is a recurrent mood disorder that usually affects people the hardest during the winter months . It is regarded as a subtype of general depression, and it shares some similarities with bipolar depression .
Seasonal affective disorder is a form of depression that is associated with seasonal changes, especially the shorter days and reduced sunlight exposure during the winter months. People who suffer from SAD, a severe form of the winter blues, experience depressive episodes during the same timeframe each year. The symptoms typically start in late fall and continue until early spring. There is a rare form of SAD called summer depression that affects people during the warmer months.
Who is affected by Seasonal Affective Disorder?
Approximately 5 percent of the U.S. population suffers from the winter blues. Women are four times more likely to be affected than men. Most people experience symptoms for the first time between the ages of 20 and 30, but some people are affected earlier. For others, it might start later in life if they move to a region with a colder climate.
Try new Winter Mood Optimization Kit for FREE: uVitals has developed & clinically tested a new Winter Mood Kit: A winter blues support supplement & specialist light therapy toolkit that will keep you healthy, productive and of elevated-mood during cold + dark winter months.
We want to get the kit in the hands of users who can provide us critical feedback so we are providing FREE samples* to those who apply to our beta program by clicking here.
What are the symptoms of Winter Blues & Seasonal Affective Disorder?
Seasonal affective disorder affects people differently, and the symptoms may vary from person to person. The severity of the symptoms can be relatively mild, or they can be overwhelming and interfere with the ability to function normally.
Typically, symptoms get worse as the winter progresses, and it begins improving as it gets closer to the spring. January and February tend to be the most difficult months for people in North America. A small percentage of SAD patients that also suffer from bipolar depression, experience symptoms in phases that are separated by “manic” periods of happiness, high energy, and increased sociability .
Since seasonal affective disorder is a type of depression, it has many similar symptoms . You might experience some of the following.
- Feelings of hopelessness
- Thoughts of suicide
- Loss of appetite
- Changes in speech patterns
- Increased pain sensation
- Urge to avoid social contact
- Loss of sex drive
Along with the symptoms of depression, you might also experience the following.
- Excessive daytime sleepiness
- Inability to perform daily tasks
- Increase in appetite for starchy carbohydrates and sweets
- Difficulty concentrating
How is Seasonal Affective Disorder diagnosed?
It can be difficult to tell if someone is suffering from general depression or if it’s the winter blues. The most important clue is the time of the year when you begin experiencing your symptoms. Your healthcare professional will do a physical and psychological evaluation, and they’ll ask about your history with symptoms of depression.
To be diagnosed with seasonal depression, you must meet the following criteria.
- Experience symptoms during a specific season for at least two years or more.
- Not experience those symptoms during any other season.
- Not have any other contributing factors for depression during the season with symptoms (like being away from your family, seasonal unemployment, etc).
Is Seasonal Affective Disorder a milder form of regular depression?
SAD is a form of depression. It is not a milder version, and it can cause symptoms that are as severe as other types of depression. The most significant difference is that SAD symptoms go into full remission during the warmer months (unless you suffer from summer SAD).
What causes Seasonal Affective Disorder?
Researchers haven’t been able to decide on any conclusive evidence for what causes seasonal depression. However, it is believed that a lack of adequate sunlight, and consequently vitamin D, might be the leading cause of the winter blues (since they are both vital to your brain functioning properly).
Sunlight and darkness are both responsible for triggering different hormones in your body. Sunlight induces the brain to release a hormone called serotonin , which is associated with elevated mood levels. It’s commonly known as the “happy hormone.” Vitamin D also plays an essential role in the synthesis of serotonin . At night, your eyes detect the darkness, and it signals the brain to release a hormone called melatonin. Melatonin is responsible for making you feel drowsy and helping you fall asleep .
When you don’t get enough sunlight and vitamin D, your hormone schedule is disrupted. Your serotonin levels might drop, and your melatonin levels might increase.
A drop in serotonin can affect your mood , and it has been linked to depression. Brain scans on people who suffer from seasonal affective disorder have shown that they had lower levels of serotonin during the winter than people that didn’t suffer from it . Additionally, increased melatonin production can cause you to feel lethargic and sleepy .
Recent studies on small mammals have suggested an alternative explanation for seasonal affective disorder. When sunlight appears later in the morning, there is an increase in morning melatonin levels. When this extra melatonin interacts with a part of the brain called the hypothalamus, it significantly suppresses the production of the active thyroid hormone. Thyroid hormone regulates all sort of functions in the body, including mood, appetite, and energy. Disruption in the active thyroid hormone might be a cause of seasonal depression .
What increases the risk for Seasonal Affective Disorder?
The following might increase your risk of developing seasonal depression
- Being female – Of all the people that suffer from the winter blues, four out of five are women. It isn’t exactly clear why women are affected more than men. It’s possible that serotonin production is affected by fluctuating levels of estrogens. Since women have more estrogen than men, that might explain why they are more susceptible to seasonal depression .
- The ZBTB20 gene – There’s some research that suggests that people with a gene called ZBTB20 are at higher risk of seasonal affective disorder . This gene might play a role in how the serotonin and melatonin levels are affected by a shorter day, causing it to be a risk factor for SAD. However, the evidence isn’t conclusive. .
- Living far from the equator – Seasonal depression is more prevalent in people that live farther away from the equator, due to the lower amount of sunlight they get during the winter months.
- Having gut health issues – Recent studies have suggested that gut health is closely related to how the brain functions, and it is referred to as the gut-brain-axis . Disturbances in the gut can affect how the brain functions , and increase the risk of seasonal affective disorder.
Are there any side effects or long term complications?
The side effects of SAD are similar to that of other types of depression if left untreated. Although it’s a mental health disorder, it can affect your physical health in various ways.
Having the winter blues can lead to overeating, resulting in unhealthy weight gain. On the other hand, it can also cause a loss of appetite, leading to nutrient deficiencies. Stress resulting from depression can constrict your blood vessels, raising your risk of cardiovascular diseases. It can also weaken your immune system, leaving you more susceptible to other illnesses, like the common cold.
Antidepressants & conventional remedies for Seasonal Affective Disorder
Antidepressants are the most commonly used conventional remedy to treat seasonal affective disorder.
SAD is believed to be caused by a dysfunction in brain serotonin levels. Second-generation antidepressants known as SSRIs (Selective Serotonin Reuptake Inhibitors) are used to restore normal serotonin levels.
Serotonin is a neurotransmitter (a chemical messenger), and it carries signals from one brain cell to another. During this process, SSRIs block the serotonin from getting reabsorbed in the brain, making more of it readily available.
Restoring serotonin might positively affect mood, and improve seasonal depression symptoms. SSRIs are generally used as a preventative measure, along with natural remedies like light therapy .
Besides SSRIs, antidepressants such as Fluoxetine, Bupropion, Sertraline, and Agomelatine have been reported to be effective against depression. They work best when treatment is started at the end of summer, or several weeks before the date of regular onset of seasonal depression symptoms .
Possible side effects of SSRIs include fatigue, nausea, stomach issues, vertigo, sexual dysfunction, headaches, and blurred vision. Many side effects might disappear after the initial period of treatment. In some cases, they may require you to seek other alternatives, if they are too severe.
Natural remedies to treat Winter Blues
The repetitive nature of seasonal affective disorder makes it predictable, and it helps in devising a treatment plan. However, the exact causes are still being researched. It is believed that only comprehensive interdisciplinary research will give us a better understanding of how to treat SAD.
If you’re susceptible to seasonal affective disorder, you can try the following natural remedies to prevent or improve your symptoms.
Bright light therapy (BLT)
Bright Light therapy (BLT), also referred to as light therapy or phototherapy, is the most widely used natural treatment for seasonal affective disorder. It is usually the first line of treatment .
One of the leading causes for winter blues is suspected to be reduced serotonin production in your brain, caused by a lack of natural environmental light. BLT seeks to replace that light, by using a light box that emits full spectrum light that is similar to sunlight.
A lightbox, sometimes called “SAD Lamps”, with fluorescent bulbs is placed behind a UV-light shield. You sit in front of the light daily for 20-60 minutes in the morning, during the symptomatic months. The goal is to provide you with a dose of 10,000 lux of light , which is considered optimal exposure for fighting SAD symptoms. You should start feeling better within a few days, and experience significant improvement within two weeks .
SAD lamps to use for BLT are available on Amazon & commercially, but Dr. Janna Gordon-Elliott, a psychiatrist at Weill Cornell Medicine and New York-Presbyterian, cautions in a NYmag article that SAD lamps aren’t regulated by the FDA (Food & Drug Administration). She advises that a good SAD lamp should be of adequate size (a good light surface should be at least 12 inches–by–18 inches); have the correct brightness levels (10,000 lux is ideal); have good viewing angles (it should be positioned above your eyes and at a slight downward angle to minimize glare); and it should definitely be UV blocking (any decent SAD light should have a built-in UV filter and be labeled “UV-Free“).
The Northern Light Technology Boxelite-OS Bright Light Therapy Box is one of the only SAD lamps available that matches all of these criteria. It has a large surface area and is rated 10,000 lux at 14 inches, meaning you get 10,000 lux when you are 14 inches away from the light. Many other lights advertise a 10,000 lux rating but you really only get that if your head is right in front of it, and at the exact right position, unlike the Boxelite-OS. It can be positioned perfectly using the adjustable height & tilt in order to minimize glare, and it is UV-free. The CET (Center for Environmental Therapeutics) is the leading authority on SAD & light therapy, and they have officially endorsed the Boxelite-OS. They even worked directly with the manufacturer to build the light box to their strict specifications.
Ideally, you should seek the supervision of a trained professional to administer light therapy as they will tailor a therapy program specifically to you, according to your sleep-wake patterns, any side effects, and preferences. Be aware that the side-effects of BLT can include eyestrain, headaches, irritability, and difficulty sleeping . However, they are generally mild and quickly improved by changing the dose of light exposure, which is why purchasing a SAD Lamp that meets the right standards is a viable option with minimal risk.
Light therapy is not recommended if you have a history of retinal diseases, or if you’re currently on medications that increase retinal sensitivity to light.
Cognitive behavioral therapy (CBT)
CBT is used to reprogram the way you think about challenges you find overwhelming. It aims to improve negative thought patterns by breaking them down into smaller parts and replacing them with positive ones . CBT is beneficial in treating many forms of depression, including seasonal affective disorder.
To change how you might think of winter, CBT uses something called “pleasant activities” scheduling. The idea is that if you schedule and take part in activities that you enjoy, you may feel better . And by feeling better while it’s still winter, you might be able to change how you think about winter itself, alleviating some symptoms of seasonal depression.
CBT is typically administered in 90-minute sessions. It’s done twice a week for six weeks, in a group format. One study has shown two sessions of CBT per week was as helpful as 30 minutes of 10,000 lux of light therapy each morning during the same period . Another study tracked 177 SAD patients that were either given CBT or light therapy for six weeks. Over the following two winter seasons, the CBT group observed higher levels of improvement . Furthermore, for patients that had a return of symptoms, the CBT group had milder symptoms than the light therapy group.
According to Kelly Rohan, the lead author of both the studies mentioned above, the reason might be that CBT equips people with internal tools they can use to control their emotions. Light therapy on the other hand, while helpful, only relies on external stimulation.
Components of CBT have been adopted by other forms of therapy to address mood disorders and lack of energy. Patients are given tools to improve their diet, manage stress, increase exercise, and be more social. These methods are aimed to counter the negative behavior patterns that make the winter blues worse.
The effect of food & diet on winter blues
What you eat is one of the most significant factors that determine how you feel and function. And it’s extra important to support your body with healthy nutrients when you’re not feeling your best.
One of the symptoms of SAD is an increased craving for starchy carbohydrates and sweets. However, they might make your symptoms worse. It’s better to eat high-quality lean proteins, leafy greens, and healthy fats. If you absolutely must eat carbs, choose healthy complex carbohydrates like sweet potatoes, or whole grain brown rice.
Here are some foods that will help your body function optimally, maintain balanced hormone levels, and fight symptoms of SAD.
- Dark leafy greens – Kale, broccoli, and spinach are excellent sources of antioxidants and vitamins. Studies have found some correlation between higher levels of antioxidants with a reduction in stress .
- Salmon – Wild caught salmon is one of the most nutrient-rich foods in the world. It’s a great source of protein, omega-3 fatty acids, and other beneficial nutrients. Omega-3s supports many vital functions in the body, and regular consumption has been linked with a lower risk of depression . It’s interesting that the prevalence of SAD is lower in Iceland than on the East coast of the United States, even though Iceland has shorter days during winter. There is a theory that they have a lower risk of the winter blues because of their high consumption of fish and omega-3s.
- Avocados – Avocados are a nutritional powerhouse. They provide almost 20 essential nutrients including vitamins B and E, potassium, folate, and more. Avocados can help regulate your blood sugar levels, and avoid cravings for sweets by keeping you full for longer . Steady blood sugar levels might help keep your mood stable.
- Oysters – Around 6 medium oysters provide you with 3 times the daily recommended value of zinc. Zinc plays an essential role in the body’s response to stress. People suffering from depression are often found to have low levels of zinc. Supplementation with zinc has also been shown to help with symptoms of depression .
- Dark chocolate – Eating dark chocolate can give your mood a much-needed boost. Dark chocolate contains magnesium and zinc. Magnesium is essential for many biochemical processes in your body, and being deficient has been associated with depression in both humans and animals . The catch is that you have to eat dark chocolate that is 70 percent or more pure cacao for best results.
- The Mediterranean diet – A study in Spain (with more than 4000 men and 5000 women) have found that men were possibly at a higher risk of depression if their diet lacked adequate folate. For women, it was a lack of B12 . Eating a Mediterranean diet will ensure that you get plenty of both vitamins, and it might reduce your risk of depression . You get folate from leafy greens, fruits, and nuts. B12 is found in lean protein such as fish, chicken breast, etc.
- Gut friendly foods – The health of your gut is closely related to how your brain functions. If your gut is disturbed, you might be at a higher risk of developing depression and anxiety . You can keep your gut healthy by consuming enough probiotics and prebiotics. Probiotics are the beneficial bacteria in your stomach, and you can get them from yogurt and fermented foods (kimchi, sauerkraut, etc.). Prebiotics are what probiotics feed on to thrive in your gut. Bananas and garlic are good sources .
- Minimize junk food – Lastly, it’s not just what you eat, but also what you avoid that is important. Consuming high amounts of processed sugar has been linked to higher risks of depression , and they can make your SAD symptoms worse.
A healthy diet will provide your brain with the nutrients that it needs to function better. However, it is not meant to be a stand-alone method of treatment, and it works best when it’s only one part of a larger treatment plan for seasonal affective disorder.
Aerobic exercise, yoga, and meditation
Aerobic exercise can stimulate growth in brain cells
Aerobic exercise is any kind of physical activity with sustained effort, and it can range from low to high intensity. Examples include jogging, swimming, cycling, and rowing. They strengthen the heart and lungs, and they improve how your body uses oxygen.
Aerobic exercise has been found to be associated with a significant reduction in depression severity , and they can be used to improve seasonal affective disorder symptoms. Combining light therapy with an exercise program is believed to be most beneficial.
The ideal form of aerobic exercise to treat depression seems to be low-intensity workouts done over an extended period. It encourages the release of proteins known as neurotrophic , which causes new nerve cells in your brain to grow and connect with each other. The newly formed connections in your brain support growth in the hippocampus, the part of the brain that regulates how you feel. Neuroscientists have found that the hippocampus is smaller in people that suffer from depression than in those who don’t . So, stimulating growth in that part of your brain can help relieve some of the winter blues symptoms .
Getting started can be challenging, since you might have disturbed sleep, less energy, increased pain sensations, etc. These physical symptoms can result in a lack of motivation to exercise. The key is to start small and keep building on it. Maybe you can start by walking around the block. Then do it twice, and then run around the block. Soon, you might find yourself jogging for a mile. Pick a type of exercise that you actually enjoy, since it works best if you keep it up long-term.
Yoga can help you respond better to stress
Yoga is a practice that aims to integrate both your mind and body with physical poses (known as asanas), controlled breathing, and a period of intentional relaxation. Yoga originated from ancient India, but it has been growing in popularity worldwide over the last few decades. One survey found that around 7.5 percent of the U.S. population has tried yoga at least once.
According to the Harvard Mental Health Letter, reviews of yoga practices have found that they can decrease the negative impacts of an exaggerated stress response . Yoga increases your heart rate variability (HRV) which is the measurement of change in time between successive heartbeats. A higher HRV will help your body adapt better to stress. Since stress is a significant symptom of seasonal affective disorder, being able to better cope with it might help you feel better overall.
It is likely that there is a yoga studio somewhere close to you. You can search “your city+yoga studio” on Google. Check their schedule and pick a beginner level class if it’s your first time. If there are no studios close by, there are plenty of free instructional videos on the internet. All you need is a mat, a glass of water, and you’re all set.
Meditation combined with exercise can reduce depression symptoms
Meditation is a practice that engages your attention on the present moment, by focusing on a specific object, thought, or activity. It is often referred to as mindfulness. There’s some evidence to suggest that meditation, when coupled with physical exercise, can significantly help reduce symptoms of depression.
According to a Rutgers University study, students that meditated and exercised twice a week for two months experienced a 40 percent reduction in depression symptoms . The researchers found that students combining the two practices were better equipped not to get overwhelmed by negative emotions.
You can start with a session of meditation, and then do 30 minutes running, swimming, etc. There are multiple meditation techniques, but one of the simplest ones is to focus on your breath as you inhale and exhale. If your thoughts start drifting, which is totally normal, just gently bring your focus back on your breath. Ideally, you’ll want to meditate for 30 minutes, but you can always start smaller and build up.
Get some sunlight
Since the lack of natural light is thought to be one of the causes of winter blues, it just makes sense that getting some sunlight might help. The problem is, how do you get sun exposure if you live in a place with limited sunlight during the winter?
If possible, you can take a vacation. Go someplace that is closer to the equator, and you’re likely to get the right amount of sunlight. Additionally, taking a few days to relax and leave your problems behind might help your overall mood.
If a vacation isn’t possible, try getting as much sun as possible where you live. Chances are, there’s some sunlight even during winter. If you’re at work during that time, try to take your breaks outside.
Vitamin D and Seasonal Affective Disorder
Vitamin D is unique because it is both a vitamin, and an essential steroid hormone. It is produced by the skin when it is exposed to sunlight . Vitamin D can also be obtained from certain foods such as fatty fish, eggs, and dairy products .
There is mounting evidence that shows an established association between vitamin D deficiency and behavioral disorders like seasonal affective disorder. Research has shown that individuals with an optimal level of vitamin D have a lower risk of developing depression .
How vitamin D deficiency is linked to depression
When we get vitamin D from sunlight or dietary sources, the body activates it by converting it into what is known as Calcitriol. Calcitriol then needs to attach to a receptor in the body known as vitamin D receptor (VDR) to carry out many of its bodily functions.
The association of vitamin D with depression can be explained by the presence of VDRs in the limbic system. The limbic system is a part of the central nervous system that plays a crucial role in motivation, emotion, and other behavioral factors . VDRs are also present in the hippocampus, a part of the brain that is associated with depression when it’s not functioning correctly .
There’s another theory called the “phenotypic stability hypothesis” that attempts to explain how vitamin D functions to reduce the risk of depression. According to this hypothesis, vitamin D controls the expression of genes that are responsible for maintaining a stable equilibrium between calcium ions (Ca2+), and reactive oxygen species (ROS). Lack of vitamin D results in elevated levels of Ca2+ and ROS in the neuronal cells, which has been linked to depression .
Vitamin D also regulates the production of the neurotransmitters dopamine and serotonin (chemicals that carry signals between nerve cells in the brain) and protects against their depletion [ 46]. Inadequate levels of vitamin D can affect dopamine and serotonin production, and have a negative effect on the function of the brain.
How to take vitamin D to treat seasonal affective disorder
Vitamin D supplementation can improve how the brain functions, and potentially prevent or improve symptoms of seasonal affective disorder. It is especially vital if you live in areas with limited sunlight during the winter, or if you don’t get enough natural light due to your work schedule.
Over-the-counter vitamin D supplements are readily available with a recommended daily allowance of 400–1000 IU, depending on age. You can also have your vitamin D levels checked at a lab, and if you’re deficient, you should speak to your doctor for recommended daily levels.
Some studies have shown that combining supplementation of vitamin D and vitamin K2 is more effective in the treatment of depression. Vitamin K2 is involved in the synthesis of lipids that are highly concentrated in brain cells, and MK-4 (a homolog of vitamin k2) fights against oxidative stress and inflammation . Vitamin K2 also normalizes blood glucose levels to reduce anxiety, and it has been shown to have antidepressant effects .
Another reason why the combination of vitamin D and K2 is beneficial is the role of calcium. Calcium helps deliver messages from the brain to various parts of the body. Vitamin D helps absorb calcium from your diet , and vitamin K2 plays a role in regulating necessary calcium levels in your body .
Final thoughts on Winter Blues & Seasonal Affective Disorder
Sometimes it can be difficult to know if you have seasonal affective disorder, or if you’re merely a bit “down” because of the cold and gloomy weather. If you suspect that it’s more than a simple case of feeling sluggish, you should seek help. You can talk to your friends and family, or reach out to a health professional. Even if they can’t diagnose you with seasonal depression immediately, they can help you get on a path to feeling better.
You can try several of the natural remedies mentioned in this article, like cognitive behavioral therapy (CBT), exercise, a healthy diet, vitamin D supplements, and more. If none of that helps, you can ask your doctor if antidepressants might be right for you. And if you ever have thoughts about harming yourself, please call the suicide prevention hotline in your country immediately (800-273-TALK if you’re in the USA).
Get the uVitals Winter Mood Optimization Kit for FREE: we have developed the Winter Mood Kit: A winter blues support supplement & specialist light therapy toolkit that will keep your mood up and let you be happy & productive during cold + dark winter months!
We want to get the Winter Blues toolkit in your hands to provide feedback, so we are giving FREE samples* to those who apply to our beta program by clicking here.
- ^ https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874241/
- ^ http://www.mentalhealthamerica.net/conditions/sad
- ^ https://www.nhs.uk/conditions/seasonal-affective-disorder-sad/symptoms/
- ^ https://www.psychiatry.org/patients-families/depression/seasonal-affective-disorder
- ^ https://www.psychologytoday.com/us/conditions/seasonal-affective-disorder
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3779905/
- ^ https://www.ncbi.nlm.nih.gov/pubmed/25713056
- ^ https://www.healthline.com/nutrition/melatonin-and-sleep
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4728667/
- ^ https://www.ncbi.nlm.nih.gov/pubmed/27353308
- ^ https://www.ncbi.nlm.nih.gov/pubmed/26994750
- ^ https://www.sciencedaily.com/releases/2015/03/150306144555.htm
- ^ https://healthcare.utah.edu/the-scope/shows.php?shows=1_qarwlqvf
- ^ https://www.nature.com/articles/s41398-018-0246-z
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6032096/
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3004726/
- ^ https://bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-017-1403-2
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4673349/
- ^ http://www.mdpi.com/1422-0067/16/1/1111/htm
- ^ https://my.clevelandclinic.org/health/diseases/9293-seasonal-depression/management-and-treatment
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367209/
- ^ https://www.rogelcancercenter.org/breaking-habits-beating-us/pleasant-activities
- ^ https://ajp.psychiatryonline.org/doi/full/10.1176/appi.ajp.2015.14101293
- ^ https://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2015.15060773
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3539819/
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3512361/
- ^ https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-12-155
- ^ https://www.psychologytoday.com/us/blog/evolutionary-psychiatry/201309/zinc-antidepressant
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986464/#sec4-nutrients-10-00584title
- ^ https://www.webmd.com/depression/guide/diet-recovery#2
- ^ https://www.hopkinsmedicine.org/health/healthy_aging/healthy_body/the-brain-gut-connection
- ^ https://www.mayoclinic.org/healthy-lifestyle/consumer-health/expert-answers/probiotics/faq-20058065
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532289/
- ^ https://www.healthline.com/health-news/mediterranean-diet-may-lower-risk-of-depression
- ^ https://www.ncbi.nlm.nih.gov/pubmed/24164734
- ^ https://www.medicalnewstoday.com/articles/296188.php
- ^ https://www.health.harvard.edu/mind-and-mood/exercise-is-an-all-natural-treatment-to-fight-depression
- ^ https://www.health.harvard.edu/mind-and-mood/yoga-for-anxiety-and-depression
- ^ https://www.nature.com/articles/tp2015225
- ^ https://asu.pure.elsevier.com/en/publications/photoperiodic-and-circadian-bifurcation-theories-of-depression-an
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4011048/
- ^ https://academic.oup.com/jcem/article/99/3/757/2537114
- ^ https://www.tandfonline.com/doi/full/10.1080/19390211.2017.1334736
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5613455/
- ^ http://pharmrev.aspetjournals.org/content/69/2/80
- ^ http://journals.sagepub.com/doi/pdf/10.1177/2050313X14561570
- ^ https://www.ncbi.nlm.nih.gov/pubmed/22419547
- ^ https://www.degruyter.com/downloadpdf/j/folmed.2016.58.issue-4/folmed-2016-0032/folmed-2016-0032.pdf
- ^ https://www.healthline.com/health/8-fast-facts-about-calcium#recommended-amount
- ^ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566462/