A New "Pass" to Sleep: Cognitive Shuffling | Serial Diverse Hypnagogia-Pass

It's 3 a.m. Your body is exhausted, but your mind won't switch off. One thought pulls the next — a conversation you keep replaying, tomorrow's to-do list, a worry that loops back on itself. The harder you try to shut it down, the louder it gets. If that sounds familiar, you're dealing with one of the most common reasons people can't fall asleep: a racing mind at night.

This post looks at why that happens, how many people it affects, and the sleep-science idea our sessions are built on — the cognitive shuffle, and our on-screen adaptation of it, the Serial Diverse Hypnagogia-Pass.

What is sleep anxiety?

"Sleep anxiety" isn't a single clinical diagnosis so much as a familiar pattern: the moment you lie down, your mind speeds up instead of slowing down. Nighttime anxiety, overthinking at night, and racing thoughts at night all point to the same core experience — a mind that stays switched on exactly when you need it to power down.

The most influential scientific account of why this becomes self-sustaining comes from psychologist Allison Harvey's cognitive model of insomnia (Harvey, 2002). In her model, the trouble starts with excessively negative, worry-toned thinking — often worry about sleep itself, and about how a bad night will wreck the day ahead. That worry triggers two things at once: physical (autonomic) arousal and emotional distress. Once you're aroused and anxious, you begin scanning for threats — checking the clock, monitoring your body for proof you're still awake, noticing every fresh reason to worry. That selective attention distorts how you read the night, which feeds still more worry. The loop keeps itself alive.

Sleep researchers call this pre-sleep cognitive arousal, and it's one of the most consistent findings in the field: people who struggle to sleep show heightened cognitive arousal — worry and rumination — in the minutes before sleep (Riemann et al., 2010). In plain terms, the problem is often not the body's inability to sleep. It's a mind that won't stop narrating.

This matters for what actually helps. If the engine of the problem is a self-feeding thought-loop, then the useful question isn't "how do I force myself to sleep?" It's "how do I give my mind something to do that doesn't build into a story?" That reframing — from forcing sleep to interrupting the narrative — is the whole basis of the method below.

How many of us are affected by a racing mind at bedtime?

More than most people assume.

In the most-cited review of its kind, sleep epidemiologist Maurice Ohayon found that about one-third of the general population reports at least one insomnia symptom, roughly 9–15% report those symptoms plus daytime consequences such as fatigue or trouble concentrating, and about 6% meet the full diagnostic criteria for insomnia (Ohayon, 2002). Later work lines up with this. Population studies commonly cite around 30% of adults reporting sleep disruption and roughly 10% meeting criteria for insomnia disorder (Roth, 2007), and a 2022 review put insomnia-with-daytime-symptoms at 10–15% (Morin & Jarrin, 2022).

Whichever definition you use, the takeaway is the same: difficulty sleeping — very often driven by exactly the racing-mind pattern described above — is one of the most common health complaints there is. And it travels closely with anxiety: worry and disturbed sleep reinforce each other, which is part of why "I can't sleep" and "I can't switch off" so often show up together.

So if you're lying awake right now — whatever brought you to this page — you are very much not the exception.

What is SDI, and what is the Serial Diverse Hypnagogia-Pass?

SDI — Serial Diverse Imagining — is a bedtime technique developed by Dr. Luc Beaudoin at Simon Fraser University, better known by its popular name, the cognitive shuffle (Beaudoin, 2013; 2014). The idea follows directly from Harvey's loop. If a racing mind stays awake by telling itself a continuous story, then the way to interrupt it is to feed it a stream of items that refuse to connect.

In practice, you bring to mind a series of ordinary, unrelated objects — apple, then umbrella, then ladder, then whale — one after another, with no thread linking them. Because the images are diverse and deliberately incoherent, no narrative can assemble itself, and there is nothing for worry to grab onto. Beaudoin calls the resulting mental state "super-somnolent": a scattered, drifting, image-based kind of thinking that resembles the way the mind naturally wanders as it falls asleep (Beaudoin, 2014). In a study presented at SLEEP 2016, he and colleagues tested the task with 154 university students who reported trouble shutting their brains off at bedtime (Beaudoin, Digdon, O'Neill & Rachor, 2016). This mind-shuffling logic is what people usually mean by "cognitive shuffle sleep."

The cognitive shuffle is elegant — but classic versions ask you to imagine the words yourself, and that is exactly where the technique breaks down for some people:

When anxiety hijacks the imagery (control failure). The imagery works fine, right up until worry grabs the wheel and steers every picture back toward whatever you're anxious about. For these minds, being asked to visualize can hand anxiety one more thing to work with.

When you can't visualize at all (capacity failure). Roughly 1% of people — rising to around 4% under broader criteria — have aphantasia: little or no voluntary visual imagery, a "blind mind's eye" (Zeman, Dewar & Della Sala, 2015). Asking them to "picture an apple" asks for something they simply cannot produce.

This is the gap the Serial Diverse Hypnagogia-Pass is built to close. Instead of asking your mind to generate each image, our sessions supply it directly: a diverse, unrelated word paired with a matching icon, shown in sequence on a near-black screen — no talking, just soft background sound. The mechanism is still Beaudoin's — a serial, diverse, incoherent stream that gives no story a foothold — but the most fragile step, mental image-generation, is removed. There is nothing for anxiety to derail, and nothing to visualize for people who can't. You watch instead of imagine. Some sessions also pair the on-screen shuffle with a slow, steady breathing rhythm of about six breaths a minute, so the approach reaches the body as well as the mind.

That is also where the name comes from. Hypnagogia is the drifting, half-dreaming state between waking and sleep — the very target Beaudoin's method aims for. The "pass" is the route we lay down through it, on screen: one word, one image, and then the next.

An honest note on the science

We think it matters to be clear about what's established and what's ours. The core mechanism — that a stream of semantically unrelated stimuli disrupts the narrative thinking that keeps a mind awake — is grounded in Beaudoin's published work on serial diverse imagining. Supplying the image on screen rather than having you generate it is our own extension of that idea; it is not something the original SDI research tested directly. So we describe how the method is designed to work, and we don't make promises about results. Sleep is personal, and what helps one racing mind may do little for another.

Try a session

If your search history lately reads like "how to stop racing thoughts at night," "how to stop overthinking," or "how to calm your mind" — the sessions on this site are built for precisely that pattern. Press play, let the words and icons pass by, and give your mind something to follow instead of a story to build. If you try one, we'd genuinely like to hear how it went for you — your story helps us understand who this works for and who it doesn't.

References

Beaudoin, L. P. (2013). The possibility of super-somnolent mentation: A new information-processing approach to sleep-onset acceleration and insomnia exemplified by serial diverse imagining. Cognitive Science Research Project, Simon Fraser University.

Beaudoin, L. P. (2014). A design-based approach to sleep-onset and insomnia: Super-somnolent mentation, the cognitive shuffle and serial diverse imagining. Paper presented at the 36th Annual Conference of the Cognitive Science Society, Québec, Canada.

Beaudoin, L. P., Digdon, N., O'Neill, K., & Rachor, G. (2016). Serial diverse imagining task: A new remedy for bedtime complaints of worrying and other sleep-disruptive mental activity. Poster presented at SLEEP 2016 (American Academy of Sleep Medicine & Sleep Research Society), Denver, CO.

Harvey, A. G. (2002). A cognitive model of insomnia. Behaviour Research and Therapy, 40(8), 869–893.

Morin, C. M., & Jarrin, D. C. (2022). Epidemiology of insomnia: Prevalence, course, risk factors, and public health burden. Sleep Medicine Clinics.

Ohayon, M. M. (2002). Epidemiology of insomnia: What we know and what we still need to learn. Sleep Medicine Reviews, 6(2), 97–111.

Riemann, D., Spiegelhalder, K., Feige, B., Voderholzer, U., Berger, M., Perlis, M., & Nissen, C. (2010). The hyperarousal model of insomnia: A review of the concept and its evidence. Sleep Medicine Reviews, 14(1), 19–31.

Roth, T. (2007). Insomnia: Definition, prevalence, etiology, and consequences. Journal of Clinical Sleep Medicine, 3(5 Suppl), S7–S10.

Zeman, A., Dewar, M., & Della Sala, S. (2015). Lives without imagery – Congenital aphantasia. Cortex, 73, 378–380.