What is cognitive defusion and how does it help insomnia?

Cognitive defusion is an ACT technique that creates psychological distance from distressing thoughts by teaching you to observe them as passing mental events rather than orders you must obey. In insomnia, thoughts such as ‘I’ll never cope tomorrow’ or ‘there must be something wrong with me’ typically drive urgent action — checking sleep trackers, forcing relaxation, or catastrophising about health. Cognitive fusion, the opposite of defusion, means these thoughts control behaviour automatically. Defusion techniques — noticing ‘my mind is telling the “I’ll be useless” story again’ rather than accepting the content as fact — reduce that automatic behavioural pull without requiring the person to prove the thought is wrong. Evidence from a randomised comparison of ACT and CBT-I found that both approaches significantly reduced dysfunctional beliefs about sleep, but ACT produced greater reductions in anxiety and showed particular benefit in reducing avoidance behaviours and experiential resistance around sleep (Dovepress, Nature and Science of Sleep, 2023). In practice, defusion lowers the pre-sleep arousal that these thoughts generate, creating more psychological space for sleep to arise naturally. I often describe defusion to clients as learning to hold your insomnia thoughts more lightly — they don’t disappear, but they stop running the night.

What does the evidence say about ACT-I for insomnia?

The evidence base for ACT-I is now supported by randomised controlled trials and systematic reviews, demonstrating consistent reductions in insomnia severity, sleep-related worry, and experiential avoidance, with improvements maintained at six-month follow-up. A 2021 randomised study by Zakiei et al. (Life, Basel) found that ACT significantly improved sleep quality alongside meaningful reductions in experiential avoidance and improvements in emotion regulation in people with insomnia. A 2024 RCT comparing ACT-I combined with bedtime restriction against CBT-I in 63 patients found ACT-I clinically feasible and effective, though not significantly superior to CBT-I on primary sleep outcomes. A systematic review of 19 ACT studies confirmed ACT improved sleep duration, sleep quality, and sleep-related cognitive and emotional processes. A notable RCT reported stand-alone ACT-I significantly reduced insomnia severity and maintained improvements at six-month follow-up. The evidence tells me ACT-I is a genuinely useful option for people whose insomnia is tightly wrapped in fear and self-judgement — and in my experience, that is most of the people I work with.

How does values-based action in ACT-I help with insomnia?

Values-based action in ACT-I shifts the focus of insomnia treatment from fixing sleep to re-engaging with what matters in life, reducing the degree to which insomnia defines and limits daily behaviour. A key perpetuating pattern in chronic insomnia is life shrinkage — cancelling plans, avoiding activities, and organising everything around protecting or compensating for sleep. This avoidance deepens preoccupation with sleep and removes meaningful daytime engagement that might otherwise buffer distress. Values clarification in ACT-I asks: what kind of partner, parent, or colleague do you want to be — and what small steps toward that are possible even with a poor night’s sleep? ACT interventions were associated with significant reductions in experiential avoidance alongside insomnia severity improvements in a systematic review of 1,577 participants across 18 studies (Zakiei & Khazaie, 2020; n=1,577). When people take small, consistent action aligned with their values despite insomnia, both daytime functioning and their relationship with sleep typically improve, because sleep is no longer the sole measure of whether the day is worthwhile. I find that for many clients, the shift that matters most is not sleeping better first — it’s deciding to live more fully anyway, and noticing that sleep often follows.

Acceptance and Commitment Therapy for Insomnia (ACT-I) is an evidence-based psychological treatment for chronic insomnia. It works by building psychological flexibility — your ability to hold difficult thoughts and feelings about sleep without fighting them. Evidence from randomised controlled trials shows ACT-I reduces insomnia severity with effects maintained at 6-month follow-up. It is available in the UK as a personalised online programme from a qualified insomnia therapist trained in both ACT-I and CBT-I.

Acceptance and Commitment therapy for insomnia

You’ve probably spent a lot of time trying to fix your sleep — tracking every minute, endlessly tweaking routines, arguing with your brain at 3am — and somehow the insomnia struggle keeps circling back. Acceptance and Commitment Therapy for Insomnia (ACT‑I) offers a different way in: less fighting with your mind, more changing how you relate to thoughts and feelings so sleep has a chance to settle by itself. 1 2 The good news: it is very often used by most modern sleep therapists!

What is acceptance and commitment therapy for insomnia?

Acceptance and Commitment Therapy for Insomnia (ACT‑I) takes the core ideas of ACT and applies them specifically to the treatment of chronic insomnia. Instead of focusing on getting rid of every worry or sensation related to sleep, it aims to build psychological flexibility: your ability to stay in the present moment and choose actions that support the life you care about, even when your mind is noisy. 1

So rather than “how do I stop thinking this?”, ACT‑I asks, “how can I carry these thoughts and emotions more lightly, so they don’t run the night?” That’s where processes such as acceptance, cognitive defusion, mindfulness, and values‑guided action come in. 1 ACT‑I sits alongside cognitive behavioral therapy for insomnia (CBT‑I) in the family of behavioural and psychological treatments for insomnia, but leans less on traditional cognitive restructuring and more on changing your relationship with the experience of insomnia. 1 3

When psychological flexibility grows, insomnia symptoms may ease because there’s less performance pressure, less of a feeling we need to ‘control’ insomnia, and more room for your natural sleep system to do its job. 1 2

Clinical Pearl

How does ACT-I compare to CBT-I?

Who is ACT‑I for?

ACT‑I can be used with adults with insomnia disorder, including primary insomnia and insomnia that’s tangled up with other conditions like chronic pain, anxiety, depression, or medical illness. 1 2It’s especially relevant for adults with insomnia who:

Feel stuck in a vicious cycle of insomnia where the harder they try to sleep, the more awake they feel.
Struggle with persistent worry, rumination, or performance anxiety about sleep and daytime functioning.
Notice that attempts to control sleep‑related thoughts and emotions backfire and increase arousal.
Have completed traditional CBT‑I (Cognitive behavioural therapy for insomnia) and still feel they’re fighting their mind at night.

Because ACT‑I directly targets experiential avoidance — the understandable wish not to feel anxious, wired, or exhausted — it can be particularly helpful when people with insomnia also carry a lot of fear, shame, or frustration about their experience of insomnia.

Core components of ACT‑I

ACT‑I integrates behavioural sleep strategies with components of ACT in a way that’s designed to reduce struggle with sleep rather than add yet another list of rules. Key elements usually include:

1. The Paradox of control

You’ll cover some basics about sleep regulation, circadian rhythms, and the “paradox of control”: the more you consciously try to sleep, the more alert your system tends to become. ¹ This often helps make sense of the vicious cycle of insomnia — poor sleep leads to worry and safety behaviours, which push arousal higher and keep insomnia symptoms going. 1 2

2. Acceptance strategies

In ACT‑I, accepting insomnia doesn’t mean liking it or giving up. It means practising experiential acceptance: allowing thoughts, sensations, and emotions related to sleep to come and go without getting into a wrestling match with them. ¹ You work gently on increasing acceptance and willingness to feel what you feel at night, instead of layering “this shouldn’t be happening” on top of already‑tired nerves. 1

3. Cognitive defusion

Cognitive defusion is ACT‑language for stepping back from thoughts so they’re seen as mental events, not orders you must obey. ¹ In practice, that might look like noticing “my mind is telling the ‘I’ll never cope tomorrow’ story again” instead of automatically reacting as if it were a fact. Over time, beliefs about sleep exert less control over behaviour, including how you respond when you wake in the night or hesitate to get out of bed. 1 2

4. Values clarification and committed action

ACT‑I spends time clarifying values across life domains — relationships, work, health, creativity — and then uses those as a compass for change. ¹ Instead of doing sleep restriction or stimulus control “to win at sleep,” you’re making small, committed moves toward what matters (being more present with your kids, showing up at work with a little more self‑compassion), even while insomnia may still be around. 1 2

5. Mindfulness and present‑moment awareness

Mindfulness practices in ACT‑I are short, practical, and related to sleep — things like noticing the breath, doing a brief body scan, or watching thoughts pass like cars while you’re lying in bed. They’re used to help you contact the present moment and loosen automatic reactions to thoughts and emotions, particularly around trying to sleep. 1 4

6. Behavioural sleep strategies

ACT‑I usually includes behavioural tools you’d recognise from traditional CBT‑I — especially working with the association with the bed and time in bed re-organisation — framing them quite differently from the way CBT-I does.

The use of ACT for insomnia here means you’re working both with behaviour and with the way you respond internally, which can make these changes more tolerable for people who’ve had a long, tense relationship with bedtime.

How is ACT‑I delivered?

ACT‑I can be delivered in different formats, and the research so far has mirrored that variety:

Individual therapy: Sessions that weaves together psychoeducation, mindfulness, acceptance work, and behavioural change.
Group therapy: In one ACT‑BBI‑I trial, adults with insomnia attended six weekly group sessions combining ACT processes with behavioural insomnia techniques like stimulus control and sleep restriction. I don’t currently run groups but may again in the future.

For many people with insomnia, this flexibility means ACT‑I can be adapted around comorbid conditions, work schedules, and energy levels — which is vital when you’re already stretched thin. 1 5

Why ACT‑I? How does ACT help insomnia?

ACT‑I is built on the idea that what keeps insomnia going isn’t just lack of sleep; it’s the whole context of insomnia — how you respond to thoughts, sensations, and emotions at night and the next day.

A few key processes:

Experiential avoidance: When you spend a lot of time and effort trying not to feel anxious, wired, or exhausted, insomnia may actually get more entrenched. ¹ ACT‑I helps you practise using acceptance instead of constant avoidance, so your nervous system can step down a gear.
Cognitive fusion: When you’re fused with thoughts — “if I don’t get 8 hours, I’ll fall apart” — they drive your behaviour. Cognitive defusion techniques reduce this grip without needing to argue about whether the thought is “true.”
Values‑guided behaviour: Organising sleep‑relevant routines around what matters (rather than around fear) can boost motivation and reduce the sense that your life is on pause until insomnia is “fixed.”

Taken together, these processes such as acceptance and defusion mean ACT may help reduce pre‑sleep arousal, soften rigid beliefs about sleep, and interrupt the vicious cycle of insomnia, even if sleep isn’t perfect right away.

Evidence for ACT-I

The ACT‑I evidence base is smaller than the CBT‑I literature, but it’s no longer just a handful of case series. We now have randomised controlled trials, comparative studies, and a systematic review focused on ACT‑based insomnia interventions.

A few key findings:

In a randomised controlled trial of an acceptance and commitment therapy‑based behavioural intervention for chronic insomnia (ACT‑BBI‑I), both ACT‑BBI‑I and CBT‑I produced significant improvements in insomnia severity, sleep onset latency, wake after sleep onset, sleep efficiency, beliefs about sleep, and psychological flexibility, with gains maintained at 6‑month follow‑up.
A systematic review and meta‑analysis of the effect of acceptance and commitment therapy on insomnia and sleep quality found that ACT interventions were associated with reductions in insomnia severity and improvements in sleep quality across a range of populations.

So ACT‑I is not a miracle cure, but it looks like a genuinely useful option, particularly for people with insomnia who feel worn out by years of trying to control sleep.

How does ACT‑I compare with CBT‑I?

CBT‑I is still the gold‑standard, first‑line cognitive behavioural therapy for insomnia, recommended in major guidelines as the initial treatment for most adults with chronic insomnia. It has a long track record of improving sleep onset, night‑time wakefulness, sleep efficiency, and overall insomnia severity, with durable effects. 3

When ACT‑I and CBT‑I (or traditional CBT‑I‑style protocols) are compared directly:

Sleep outcomes: CBT‑I often shows stronger and more consistent improvements in core sleep metrics (sleep onset latency, wake after sleep onset, sleep efficiency), although ACT‑I still improves these outcomes for many individuals with insomnia. 2 3
Emotional and process outcomes: ACT‑I tends to shine on outcomes like anxiety about sleep, psychological flexibility, and experiential avoidance — the “how I’m relating to this” part of insomnia. 1 2
Clinical fit: For some people with insomnia, thought‑challenging feels invalidating or exhausting. For them, incorporating principles from acceptance and commitment therapy into the treatment of insomnia can feel more aligned and sustainable, especially when the experience of insomnia has become deeply entangled with identity and self‑criticism. 1 2

Guidelines still recommend CBT‑I as the first‑line treatment for chronic insomnia, but ACT‑I is increasingly seen as a useful alternative or companion, especially when the main pain point is the ongoing fight with thoughts and emotions rather than the mechanics of bedtime itself. 3 6

So which do you “choose”?

In real insomnia and clinical practice, this usually isn’t a strict either/or. Many clinicians blend ACT and CBT‑I together — for example, using behavioural approaches but using ACT to reduce pressure, foster acceptance, and support values‑guided action.

From a practical, human point of view:

CBT‑I is usually the first offer if the goal is to treat insomnia efficiently and you’re open to structured, behavioural work.
ACT‑I becomes especially attractive if you’ve already “done the basics,” maybe even done CBT‑I, and still feel like your nights are dominated by fear, self‑judgment, and the urge to control sleep at all costs.
ACT-I is particularly good for people who are highly anxious or who struggle with perimenopause and insomnia
Integration — ACT and CBT‑I together — often gives you the best of both worlds: solid behavioural scaffolding plus tools to soften the inner battle. This is how I work, adapted to your specific situation.

None of these approaches ask you to become a perfect sleeper or a perfect meditator. They’re simply different ways of helping your system remember what it once knew how to do: sleep, without so much effort. You can read more about how to choose between CBTI and ACTI.