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Why You Can't Sleep Even When You're Exhausted: Understanding the Link Between Sleep and Anxiety

Updated: Feb 25

It's midnight. You've been awake since 6 AM. You sat through back-to-back meetings, ran errands, cooked dinner, and finally collapsed into bed — and now you're staring at the ceiling. Your body feels like lead. Your eyes are heavy. But sleep? Nowhere to be found.


If this sounds familiar, you're not alone — and more importantly, you're not broken. There's a very specific reason this happens, and once you understand it, the path forward becomes much clearer.


Public Health Issue:

Nearly 1 in 3 adults in Canada experience sleep disturbances (Chaput et al. 2025) and nearly 1 in 5 Canadians adults experience mental health issues in any given year (Canadian Institute of Mental Health, 2025). Anxiety is the most prevalent mental illness worldwide and 1 in 4 Canadians will be diagnosed with anxiety. This does not account for the millions of Canadians who suffer in silence. 


These important statistics suggest that both sleep and anxiety are national public health issues on their own. However, emerging research suggests we should not think of these challenges separately. They are more intertwined than we think. 


What is Anxiety?

Anxiety is characterized by inflated and persistent feelings of fear and worry that are out of proportion to the actual threat, with impaired daily functioning. Common anxiety disorders include generalized anxiety disorder (GAD), panic disorder (PD), specific phobias, agoraphobia, social anxiety disorder (SAD), and separation anxiety disorder. Furthermore, anxiety-related disorders include post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD) and adjustment disorder.


Anxiety and Sleep:

More than 70 % of individuals with anxiety/anxiety-related disorders experience poor sleep quality, and exhibit sleep disturbances. In individuals with PTSD, more than 90% experience insomnia symptoms. While sleep disturbances are a defining criteria in anxiety and anxiety related disorders, insufficient sleep can instigate or further exacerbate anxiety. The brain link between sleep and anxiety is therefore a bidirectional cycle, each exacerbating the other. 


The Vicious Cycle:


Image from Xue et al. 2025
Image from Xue et al. 2025


How does Poor Sleep Impact Anxiety?


In the Brain:

  • Hypothalamic-pituitary-adrenal (HPA) axis and cortisol: The HPA axis is the body’s central stress response system. It involves a chain reaction stimulating the release of cortisol, a steroid hormone that plays a crucial role in the body’s stress response. Sleep deprivation triggers spikes in stress hormones, like cortisol, which can lead to more anxiety in the morning. 

    • Dysregulation of the HPA axis and elevated cortisol levels, reinforced by both poor sleep and anxiety, can further worsen both conditions. 



  • Brain region activity: Lack of sleep can increase activity in our fear network, including the amygdala, making the brain more sensitive to threats. Sleep disturbances can also impair the medial prefrontal cortex (mPFC), which is involved in emotional regulation. 


  • Neurotransmitter imbalances: sleep deprivation can affect neurotransmitters like serotonin and dopamine, which are involved in both mood and sleep, worsening anxiety symptoms. 


How it Might Appear in Daily Life:

  • Increased feelings of nervousness or panic

  • Difficulty managing stress during the day

  • Difficulty managing emotions and rational thinking

  • Greater vulnerability to anxiety disorders


Research shows that people who sleep less than six hours per night are more likely to develop anxiety symptoms. Even one night of poor sleep can increase anxiety levels the following day, creating a cycle that is hard to break.



How does Anxiety Disrupt Sleep?

  • Physiological arousal: Anxiety activates the sympathetic nervous system (the "fight or flight" response), releasing cortisol and adrenaline. These stress hormones raise heart rate, increase body temperature, and keep the brain in an alert state - all of which are the opposite of what the body needs to initiate sleep.


  • Cognitive hyperarousal: Anxious minds tend to ruminate — replaying worries, anticipating problems, or catastrophizing. This mental activity is incompatible with the mental quieting needed to fall asleep. Bedtime often becomes the first quiet moment of the day, which paradoxically gives anxious thoughts more space to take hold.


  • Hypervigilance: Anxiety keeps the brain scanning for threats even during sleep. This makes people more likely to wake at minor sounds or sensations, and harder to return to sleep once awake.



Brings Us Back to the Vicious Cycle....

Each condition makes the other worse, and they can compound each other’s effects. For example, anxiety can prevent a person from getting deep sleep, and deep sleep is the stage of sleep that is most effective at resetting the brain’s anxiety levels.



Breaking the Cycle:

By working on an individual’s quality of sleep, we can break the cycle and improve their mental health. Treating sleep disturbances, especially with CBT-I, can effectively alleviate both anxiety symptoms and sleep disturbances (Xue et al. 2025). Numerous professional societies including the Canadian college of Physicians, the American college of Physicians, the British Sleep Society and European research study clearly endorse CBT-I as the first line treatment for insomnia. CBT-I uses multiple evidence based strategies including good sleep hygiene, stimulus control, sleep restriction and relaxation therapy. It’s a safe and effective treatment for sleep related symptoms. 


Occupational Therapists (OTs) specialising in sleep are especially well placed health care professionals that can help individuals break the cycle by addressing both sleep and anxiety. Visit my blog post HERE to understand in greater depth how an OT specialising in sleep can help you break the vicious cycle and achieve optimal performance in meaningful occupations.






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