Understanding Cortisol: Why Trauma, Stress, and Anxiety Can Affect Your Sleep
How your body's stress response influences sleep, and why the work you do during the day can make a difference at night.
Have you ever felt completely exhausted, only to find yourself wide awake when your head finally hits the pillow?
Perhaps your mind starts replaying conversations from the day, worrying about tomorrow, or thinking about things you wish you had handled differently. Maybe you fall asleep easily but wake several times throughout the night, feeling restless or unusually alert.
For people experiencing anxiety, ongoing stress, or the effects of trauma, sleep can be particularly challenging.
You may have heard people talk about cortisol, often referred to as the body's stress hormone. But what exactly is cortisol? How does it affect sleep? And can addressing stress and anxiety throughout the day help you sleep better at night?
Understanding how your body's stress response works can help make sense of these experiences and offer hope for change.
What Is Cortisol, and Why Do We Need It?
Cortisol is a hormone your body naturally produces to help you manage the demands of everyday life. Although cortisol is often associated with stress, it isn't harmful by nature. In fact, it's essential to your health. Cortisol helps your body manage energy, regulate blood sugar, support immune functioning, and respond to physical and emotional challenges.
It also follows a natural daily rhythm. Cortisol levels typically begin rising toward morning, helping prepare your body to wake up and become alert. Levels generally decrease throughout the day and are usually lower during the early part of the night.
When you encounter something stressful, your brain communicates with your body to help you respond. Cortisol is released as part of this process, along with other changes that increase alertness and prepare you to deal with the situation; this is a normal and healthy response.
The difficulty can arise when stress is frequent, prolonged, or connected to traumatic experiences, and the body's stress-response systems become more sensitive or have difficulty adjusting to changing circumstances.
What Happens to Our Stress Response After Trauma?
Our bodies are designed to recognize potential danger and respond to it. Imagine walking across a street when a car suddenly approaches. Your heart races, your muscles tense, and your attention immediately shifts toward protecting yourself. Your body's stress response has helped you react quickly. When the danger passes, your body can begin returning toward its usual level of activity.
However, for individuals who have experienced trauma, ongoing anxiety, or prolonged stress, this process can become more complicated. Experiences such as post-traumatic stress disorder (PTSD), complex PTSD, repeated exposure to distressing events, anxiety, or stress can affect how the brain and body recognize and respond to potential threats.
Someone may find themselves constantly scanning their surroundings, anticipating problems, feeling easily startled, or having difficulty relaxing, even when they know intellectually that they are safe. Their nervous system may have become highly sensitive to reminders of danger. This doesn't mean the person is consciously choosing to remain on alert. These responses can develop as adaptations to difficult or threatening experiences.
For those living with unresolved trauma, the trauma doesn't necessarily mean that someone has too much cortisol rather it may develop0 different patterns of expression. Research has found that traumatic stress injuries can be associated with different patterns of cortisol regulation. The broader stress-response system, including the nervous system, plays an important role in how someone experiences anxiety, alertness, and sleep.
Why Can Stress and Trauma Make It Difficult to Sleep?
The ability to sleep requires more than simply feeling tired. The body also needs to make the transition from wakefulness into sleep. This involves several biological processes working together, including your internal body clock, the natural pressure to sleep that builds throughout the day, and the systems that regulate alertness. When stress or anxiety is ongoing, your mind and body may remain more alert than you would like.
You might notice that:
Your thoughts become more active when you lie down
You replay conversations or worry about what might happen tomorrow
Your body feels restless or tense despite being exhausted
You wake frequently or feel unusually alert during the night
You wake early and struggle to fall back asleep
For some people who have experienced trauma, nighttime can also bring an increased sense of vulnerability. The quiet, darkness, or reduced awareness of their surroundings may make it harder to settle.
Cortisol can be part of this picture, but it isn't the only factor. Other stress-related processes, including heightened nervous system activity, worry, and learned patterns of alertness, can contribute to disrupted sleep. Research describes this as hyperarousal, a state in which the mind or body remains more activated than is helpful for sleep. Over time, difficulty sleeping can also make stress harder to manage. Poor sleep may increase emotional sensitivity, irritability, and anxiety the following day, creating a cycle that can be difficult to interrupt.
The Backpack We Carry Throughout the Day
One way I sometimes explain the effects of everyday stress and anxiety is through the image of a backpack. Imagine starting your morning with an empty backpack. As you move through your day, different situations arise. Perhaps someone makes a comment that leaves you questioning yourself. You feel anxious about an upcoming conversation. Something doesn't go as planned. You make a mistake and begin criticizing yourself. Each experience may add something to your backpack.
Not every stressful moment becomes a lasting burden. But when we repeatedly worry about an experience, avoid dealing with a concern, or become caught in negative self-talk, the emotional weight can remain with us.
By the middle of the day, your backpack may already feel quite heavy. Then something more significant happens. Perhaps there's an argument, an unexpected problem, or another situation that triggers anxiety. Managing that experience may feel much harder when you're already carrying so much. By bedtime, you're physically exhausted, but your mind may still be occupied with the worries and emotional experiences of the day.
The backpack is a metaphor for the emotional and mental burden we can carry. It doesn't mean cortisol literally accumulates in our bodies throughout the day. What it helps us understand is how ongoing worry, unresolved concerns, and repeated stress responses can contribute to a sense of being overwhelmed and make it harder to settle at night.
Why Recognizing Anxiety Early Matters
An important part of managing anxiety is learning to recognize it when it first appears, rather than only noticing it once it becomes overwhelming.
Anxiety doesn't always announce itself clearly. Sometimes it shows up as muscle tension, irritability, restlessness, overthinking, difficulty concentrating, or an urge to avoid something uncomfortable.
It can also appear in the way we speak to ourselves. For example, imagine making a mistake at work. You might initially feel embarrassed or disappointed. But then your thoughts shift toward: “I always mess things up.” “I'm not good enough.” “Other people must think I'm incompetent.” The original situation may have been relatively small, but the meaning you attach to it can intensify your anxiety and affect how you see yourself. When these patterns happen repeatedly, they can contribute to ongoing distress, reduced self-confidence, and negative self-perception.
Learning to recognize these moments creates an opportunity to respond differently. You might begin by asking yourself:
What am I feeling right now?
What happened that brought up this feeling?
What am I telling myself about the situation?
Is there a problem I can take action to address?
If this is something I cannot change, how might I begin to accept it without continuing to struggle against it?
Sometimes the response involves solving a problem, setting a boundary, or having a difficult conversation. Other times, it involves challenging an unhelpful thought, allowing an uncomfortable emotion to pass, or showing yourself greater compassion. The goal isn't to eliminate anxiety. Anxiety is a normal part of being human. Rather, it's about developing the ability to recognize what you're experiencing and respond in ways that don't unnecessarily add to your distress.
Returning to our backpack analogy, these small moments of awareness may help us address some of what we're carrying before it becomes overwhelming.
Can the Work We Do During the Day Help Us Sleep Better at Night?
Yes, it can. The work we do to understand and manage anxiety, recognize trauma responses, change patterns of negative self-talk, and develop healthier ways of responding to stress can influence our overall emotional well-being. For individuals who have experienced trauma, therapy can also help address the memories, beliefs, emotional responses, and patterns of vigilance that developed in response to difficult experiences. Over time, these changes may reduce some of the ongoing distress and heightened alertness that interfere with sleep.
However, sleep doesn't always improve immediately, even when someone is making meaningful progress in therapy. Sometimes insomnia develops patterns of its own. A person may begin to associate bedtime with frustration, worry, or the expectation that they won't sleep. These patterns can continue even when their daytime anxiety or trauma symptoms have improved. It's also important to recognize that sleep difficulties can have other contributing causes, including physical health conditions, medications, sleep apnea, and other sleep disorders.
There Is Hope for Better Sleep
If you've been struggling with sleep for a long time, it can be discouraging. You may have tried different strategies, relied on sleep medications or other substances for relief, or wondered whether restful sleep will ever come naturally again.
The encouraging news is that sleep difficulties can improve. Understanding your stress responses, recognizing anxiety earlier, addressing unhelpful thinking patterns, and working through the effects of trauma can all be meaningful parts of recovery.
For some people, these changes help improve sleep. Others may also need treatment that directly addresses insomnia or other contributing health concerns. If you use sleep medication, any changes should be discussed with your prescribing healthcare professional. Progress may be gradual, and it may not follow a straight line. Having a difficult night doesn't mean the work you're doing isn't helping. Remember the backpack. You may not be able to prevent every stressful experience from entering your day. But you can learn to recognize what you're carrying, understand what needs your attention, and develop ways to respond before the weight becomes overwhelming.
Better sleep doesn't always begin at bedtime. Sometimes it begins with how we learn to recognize and respond to stress throughout the day. And while improving sleep can take time, you don't necessarily have to remain stuck in the same patterns forever.
For additional strategies related to sleep routines and healthy sleep habits, read our article on sleep hygiene.
References
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U.S. Department of Veterans Affairs & Department of Defense. (2025). VA/DoD clinical practice guideline for the management of chronic insomnia disorder and obstructive sleep apnea. https://www.healthquality.va.gov/guidelines/CD/insomnia/
This article is intended for educational purposes and is not a substitute for individualized medical or mental health assessment or treatment.
