Leaves on a Stream: An ACT Defusion Meditation for Watching Your Thoughts Pass
The classic ACT defusion meditation: place each thought on a leaf, let it float by, and practice watching your mind instead of being caught in it.
Reviewed by Michael Callans, MSW 
About this tool
Leaves on a Stream is one of the best known exercises in Acceptance and Commitment Therapy, used to teach cognitive defusion: the skill of stepping back from your thoughts so they have less grip on you. Instead of arguing with a thought or trying to push it away, you practice noticing it as a passing mental event, something the mind produces, rather than a command you must obey or a truth you must believe.
The exercise asks you to picture a gently flowing stream with leaves drifting on the surface. As each thought arises, you place it on a leaf and watch it float away. You do not force the leaves to move faster, and you do not try to stop the stream. When you notice you have been hooked by a thought and have stopped watching, that noticing is the exercise working: you gently return to the bank and resume placing thoughts on leaves.
Defusion does not make thoughts disappear, and it is not a relaxation technique, though people often feel calmer afterward. The point is a shift in relationship: seeing that you are the one observing your thoughts, not the thoughts themselves. With practice, this loosens the automatic pull of self-critical, anxious, or repetitive thinking, freeing you to act on your values instead of your mind's running commentary.
Defusion techniques like this one sit inside a broader body of ACT research. A meta-analysis of controlled trials found that ACT performs about as well as established treatments such as cognitive behavioral therapy for anxiety and depression, and clearly better than no treatment or treatment as usual (A-Tjak et al., 2015). Leaves on a Stream is usually taught as one tool among several rather than a stand-alone treatment, so it works best paired with values work or committed action when you are using it for a specific problem.
If a thought keeps returning with intense distress, or the exercise leaves you feeling numb or disconnected rather than gently observing, stop and bring that to a therapist trained in ACT instead of pushing through alone. Our therapist directory at /therapist/ lets you search by specialty at no cost.
References
- Hayes SC, Strosahl KD, Wilson KG. Acceptance and Commitment Therapy: The Process and Practice of Mindful Change. 2nd ed. Guilford Press; 2012.
- Harris R. The Happiness Trap. 2nd ed. Trumpeter; 2022.
- A-Tjak JGL, Davis ML, Morina N, Powers MB, Smits JAJ, Emmelkamp PMG. A meta-analysis of the efficacy of acceptance and commitment therapy for clinically relevant mental and physical health problems. Psychother Psychosom. 2015;84(1):30-36.
Cite this source
Psychology.com. (2026, September 15). Leaves on a Stream. Psychology.com. https://psychology.com/tools/leaves-on-a-stream
Leaves on a Stream FAQ
What is the Leaves on a Stream exercise for?
It teaches cognitive defusion, the ACT skill of stepping back from your thoughts and watching them come and go rather than getting tangled in them. Over time this reduces how much your thoughts control your mood and behavior.
What if I keep getting distracted?
That is the exercise, not a failure. Each time you notice you have been hooked and gently return to the stream, you are practicing the exact skill ACT is trying to build.
Is this a relaxation technique?
Not exactly. People often feel calmer, but the goal is a change in your relationship with your thoughts, not relaxation. Treat the calm as a welcome side effect, not the target.
Is my information saved?
No. Everything stays in your browser. Your entries are never uploaded or stored, and the PDF is generated on your own device.
How long should I practice Leaves on a Stream?
A few minutes is enough to feel the shift. Many people find it more useful as a short, frequent reset they return to several times a day rather than one long sitting, since the aim is building a habit of noticing thoughts, not reaching a set duration.
Does cognitive defusion help with anxiety and intrusive thoughts?
Defusion is one of the core skills taught in Acceptance and Commitment Therapy for anxiety, and research on ACT overall shows it performs comparably to established treatments like CBT. Leaves on a Stream will not stop intrusive thoughts from arising, but it can reduce how much they hook your attention and drive what you do next.