The latest research, learnings, and insight on mental health.

The Root Causes Of Depression, Anxiety, And Insomnia

What is behind depression, anxiety, and other mental health conditions? Are we prone to such conditions due to our genes? How about our upbringing? And once we are born, how much control do we have over our emotional futures? In this article, we will review some of the main reasons some people experience mental health symptoms, while others do so less severely or often.

Depression: Beyond the "Chemical Imbalance"

You've probably heard the term "chemical imbalance" when it comes to depression. While it's true that neurotransmitters like serotonin and dopamine play a role in mood regulation1, the full picture is much more complex. Factors such as genetics, environmental stressors, and even inflammation can contribute to depression.2

Genetics can predispose us to depression, with twin and family studies estimating that up to 50% of the risk for depression is heritable.3 Life events, such as trauma or prolonged stress, can also increase the risk.4 Additionally, researchers have discovered that inflammation in the body can lead to depressive symptoms, potentially due to the immune system's effect on neurotransmitter function.5

Anxiety: The Wired Brain

Like depression, anxiety is a multifaceted condition with multiple contributing factors. Genetics play a role, as individuals with a family history of anxiety disorders are more likely to experience them themselves.6 Environmental factors, such as childhood trauma or stressful life events, can also increase the risk of developing an anxiety disorder.7

Anxiety is often rooted in the brain's fear and threat detection system, which includes the amygdala and other related structures.8 Overactivation of this system can lead to persistent feelings of fear or worry, even in the absence of an immediate threat.9

Insomnia: A Cascade of Causes

Insomnia, a common sleep disorder characterized by difficulty falling or staying asleep, can have a variety of causes. Stress, anxiety, and depression are known to contribute to sleep disturbances.10 Medical conditions, medications, and lifestyle factors, such as caffeine or alcohol consumption, can also disrupt sleep.11

Moreover, insomnia may result from disruptions to our internal biological clock, or circadian rhythm, which regulates our sleep-wake cycle.12 Exposure to blue light from electronic devices before bedtime, for example, can interfere with the production of the sleep hormone melatonin and make it harder to fall asleep.13

The Interconnectedness of Depression, Anxiety, and Insomnia

Depression, anxiety, and insomnia often co-occur and influence one another. For instance, insomnia can exacerbate anxiety and depression,14 while depression and anxiety can, in turn, worsen sleep quality.15 This interplay emphasizes the importance of addressing all aspects of mental health to promote overall well-being.


Understanding the complex causes of depression, anxiety, and insomnia is the first step towards healing and growth. As we continue to learn more about the intricate interplay between genetics, environment, and biology, we can better tailor treatments and interventions to help individuals overcome these challenges. Remember, knowledge is power, and by seeking to understand ourselves and our mental health, we empower ourselves to live happier, healthier lives.

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  1. Cowen P. Serotonin and depression: pathophysiological mechanism or marketing myth? Trends in Pharmacological Sciences. 2008;29(9):433-436. doi:https://doi.org/10.1016/j.tips.2008.05.004
  2. Kendler KS, Hettema JM, Butera F, Gardner CO, Prescott CA. Life Event Dimensions of Loss, Humiliation, Entrapment, and Danger in the Prediction of Onsets of Major Depression and Generalized Anxiety. Archives of General Psychiatry. 2003;60(8):789. doi:https://doi.org/10.1001/archpsyc.60.8.789
  3. Sullivan PF, Neale MC, Kendler KS. Genetic Epidemiology of Major Depression: Review and Meta-Analysis. American Journal of Psychiatry. 2000;157(10):1552-1562. doi:https://doi.org/10.1176/appi.ajp.157.10.1552
  4. Hammen C. Stress and Depression. Annual Review of Clinical Psychology. 2005;1(1):293-319. doi:https://doi.org/10.1146/annurev.clinpsy.1.102803.143938
  5. Miller AH, Raison CL. The role of inflammation in depression: from evolutionary imperative to modern treatment target. Nature Reviews Immunology. 2015;16(1):22-34. doi:https://doi.org/10.1038/nri.2015.5
  6. Smoller JW. The Genetics of Stress-Related Disorders: PTSD, Depression, and Anxiety Disorders. Neuropsychopharmacology. 2015;41(1):297-319. doi:https://doi.org/10.1038/npp.2015.266
  7. McEwen BS. Mood disorders and allostatic load. Biological Psychiatry. 2003;54(3):200-207. doi:https://doi.org/10.1016/s0006-3223(03)00177-x
  8. Shin LM, Liberzon I. The Neurocircuitry of Fear, Stress, and Anxiety Disorders. Neuropsychopharmacology. 2009;35(1):169-191. doi:https://doi.org/10.1038/npp.2009.83
  9. Etkin A, Wager TD. Functional Neuroimaging of Anxiety: A Meta-Analysis of Emotional Processing in PTSD, Social Anxiety Disorder, and Specific Phobia. American Journal of Psychiatry. 2007;164(10):1476-1488. doi:https://doi.org/10.1176/appi.ajp.2007.07030504
  10. Baglioni C, Battagliese G, Feige B, et al. Insomnia as a predictor of depression: A meta-analytic evaluation of longitudinal epidemiological studies. Journal of Affective Disorders. 2011;135(1-3):10-19. doi:https://doi.org/10.1016/j.jad.2011.01.011
  11. Morin CM, Benca R. Chronic insomnia. The Lancet. 2012;379(9821):1129-1141. doi:https://doi.org/10.1016/s0140-6736(11)60750-2
  12. Borb AA, Achermann P. Sleep Homeostasis and Models of Sleep Regulation. Journal of Biological Rhythms. 1999;14(6):559-570. doi:https://doi.org/10.1177/074873099129000894
  13. Cajochen C, Frey S, Anders D, et al. Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance. Journal of Applied Physiology. 2011;110(5):1432-1438. doi:https://doi.org/10.1152/japplphysiol.00165.2011
  14. Alvaro PK, Roberts RM, Harris JK. A Systematic Review Assessing Bidirectionality between Sleep Disturbances, Anxiety, and Depression. Sleep. 2013;36(7):1059-1068. doi:https://doi.org/10.5665/sleep.2810
  15. Baglioni C, Spiegelhalder K, Lombardo C, Riemann D. Sleep and emotions: A focus on insomnia. Sleep Medicine Reviews. 2010;14(4):227-238. doi:https://doi.org/10.1016/j.smrv.2009.10.007

Cover photo by Tiago Bandeira on Unsplash


The latest research, learnings, and insight on mental health, curated by Dr. Hillary Lin.

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