It’s the argument with a loved one that you re-litigate in the shower, the embarrassing moment in a meeting that resurfaces just as you’re trying to sleep. A negative thought, a worry, or a mistake gets stuck in our minds, playing over and over on a seemingly endless loop—a mental replay button we can’t find the off-switch for.

This feeling of being stuck is a common human experience, but psychological science is beginning to understand it not just as a symptom of a larger problem, but as a specific mental process. This article breaks down five key scientific insights into why our brains get stuck and what this process, known as rumination, really is.

1. Rumination Affects Multiple Mental Health Conditions (Not Just Depression)

While often linked exclusively with depression, modern psychology sees rumination as a much broader mental habit. Researchers now classify it as a form of Repetitive Negative Thinking (RNT), a process with a distinct set of characteristics. According to psychologist Thomas Ehring, RNT is a style of thinking that is repetitive, intrusive, difficult to disengage from, perceived as unproductive, and captures your mental capacity.

Perhaps the most surprising insight is that this mental loop is a “transdiagnostic” process. This means it isn’t unique to one disorder but plays a key role across a wide range of mental health conditions. Research shows it’s a significant factor in:

• Post-traumatic stress disorder (PTSD)
• Anxiety disorders
• Insomnia
• Eating disorders
• Somatic symptom disorder
• Substance use disorders

This reframes “overthinking” not as a flaw specific to a single issue, but as a widespread mental habit that can affect anyone. But what is this habit, exactly? Is it a matter of willpower? The science suggests it’s less about personal failing and more about a breakdown in our brain’s control systems.

2. Why You Can’t Stop Overthinking: Understanding the Cognitive Control Problem

If you’ve ever felt frustrated for not being able to simply “stop” thinking about something, there’s a scientific reason why. Getting stuck in rumination isn’t a sign of a bad memory; it’s a problem with mental control.

Research suggests that rumination is linked to “deficits in cognitive control,” which leads to a “lack of top-down control” over negative thoughts. Think of cognitive control as the brain’s air traffic controller, responsible for directing attention and keeping intrusive thoughts from landing. In rumination, that controller is overwhelmed, allowing negative thoughts to circle endlessly. This is why willpower alone often isn’t enough to break the cycle.

“Rumination is characterized by deficits in cognitive control, leading to a lack of top-down control over the processing of negative material.”

Understanding this can be empowering. It shifts the focus from self-blame (“Why can’t I just stop?”) to recognizing a deficit in a specific cognitive skill—one that can potentially be strengthened. This lack of control helps explain how the cycle gets started, often in response to a common trigger: stress.

3. How Stress Triggers Rumination and Creates a Negative Thought Cycle

There’s a clear and powerful link between experiencing life stress and the onset of rumination. A longitudinal study by Michl and colleagues on both adolescents and adults found that exposure to stressful life events could predict a subsequent increase in rumination, sometimes even months later.

Once triggered, rumination creates what researchers Moberly and Watkins describe as a “reciprocal relationship”—a bidirectional trap. Not only does ruminative thinking lead to more negative affect (like sadness or anxiety), but negative affect also triggers more ruminative thinking. It’s a feedback loop where each element fuels the other.

Interestingly, their study also found that ruminative thinking often peaks at specific times, such as in the morning and evening, when individuals may have fewer external distractions to occupy their minds. This timing matters because it reveals when we’re most vulnerable to getting stuck in the loop.

4. Brooding vs. Reflection: The Difference Between Harmful and Helpful Rumination

Not all self-focused thinking is maladaptive. In the context of depression, rumination has traditionally been defined as “thoughts and behaviours that focus the depressed individual’s attention on his or her symptoms and the possible causes and consequences of those symptoms.”

However, modern research separates this process into two distinct styles: brooding and reflection. The distinction is critical. Brooding is a maladaptive process involving a “chronic and persistent self-focus on negative emotional states and unachieved standards.” It’s like being stuck in a muddy ditch, passively staring at the dirt walls.

In contrast, reflection is a more adaptive process of “open purposeful curiosity about the self.” This is like using a ladder to climb out and examine the ditch from above, trying to understand how you fell in and how to avoid it next time.

The failure in cognitive control discussed earlier is what allows brooding to take over. Reflection, on the other hand, represents a way of re-engaging that control in a more purposeful, curious way. An experience sampling study by Moberly and Watkins confirmed this distinction is crucial, finding that the brooding subtype was associated with higher levels of negative affect, while reflection was not.

“Brooding involves a chronic and persistent self-focus on negative emotional states and unachieved standards, while reflection represents open purposeful curiosity about the self.”

5. Co-Rumination: When Talking About Problems With Friends Makes Anxiety Worse

Rumination isn’t always a solitary activity. When we excessively hash out problems with a friend, it can become co-rumination, which researchers define as “excessively discussing personal problems within a dyadic relationship.” Imagine two friends spending hours on the phone dissecting a minor social slight. They feel closer for sharing the experience, but both hang up feeling more anxious and fixated on the problem than before they talked.

This behavior creates what researcher Amanda Rose calls a “socioemotional trade-off.” On one hand, co-rumination predicts increases in positive friendship quality and feelings of closeness. On the other hand, especially for girls, it also predicts increases in depressive and anxiety symptoms over time.

This can be seen as an external, social version of the internal vicious cycle, where friends inadvertently co-create a feedback loop of negative affect. A behavior that feels supportive and strengthens friendships can paradoxically maintain and even worsen negative emotional states, revealing just how complex this mental habit can be.

Breaking the Overthinking Cycle: What the Research Tells Us

Understanding rumination isn’t about blaming yourself for “thinking too much.” Instead, it’s about recognizing a complex mental process influenced by your cognitive control, stress levels, specific thinking style, and even your social interactions. By seeing it as a habit rather than a character flaw, the possibility of changing it becomes more real.

The research reveals that sustainable change requires more than willpower. It requires recognizing when you’ve shifted from reflection to brooding, understanding your vulnerability windows (morning and evening), and being aware of how social interactions can either help or harm your mental state.

Now that you see rumination as a mental habit, what is one small way you could interrupt the process the next time you feel stuck? Whether it’s recognizing the difference between brooding and reflection, or noticing when a conversation with a friend has shifted into co-rumination, awareness is the first step toward change.