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The light is off and the day should be over, but part of your mind is still working. There’s the email you meant to answer, the appointment you keep forgetting to book, the form you need to bring tomorrow.
Not everyone lies awake running through a list like this, but plenty of people will recognise the feeling. So here’s a small puzzle: if thinking about tomorrow’s jobs can keep you awake, what happens when you write them down instead?
Five minutes with a pencil, then lights out
A team at Baylor University’s Sleep Neuroscience and Cognition Laboratory, led by psychologist Michael Scullin, tested a version of that question in a study published in the January 2018 issue of the Journal of Experimental Psychology: General. It involved 57 healthy adults aged 18 to 30, screened for sleep disorders and medications that affect sleep, who each spent a weeknight in the lab.
Shortly before bed, participants were randomly assigned to one of two five-minute writing tasks, done with pen and paper. One group wrote down everything they needed to remember to do over the next few days. The other wrote about tasks they had completed over the previous few days.
Instead of relying on participants’ own estimates, the researchers used overnight polysomnography, which records brain activity through electrodes on the scalp. The key measure was sleep onset latency: the time it takes to fall asleep.
| Five-minute writing task | Average time to fall asleep |
|---|---|
| Tasks to complete over the coming days | About 16 minutes |
| Activities already completed | About 25 minutes |
The difference was statistically significant. But these are group averages, and individuals varied a lot: some people in both groups dropped off quickly, others took much longer. The groups also didn’t differ significantly in total sleep time or sleep efficiency, so the study shows faster sleep onset, not better sleep overall.
What would you have predicted?
The result can look obvious in hindsight, but it could easily have gone the other way. Bringing unfinished responsibilities to the front of your mind at bedtime might make you more alert, not less.
“There are two schools of thought about this,” Scullin said in Baylor’s announcement of the study. “One is that writing about the future would lead to increased worry about unfinished tasks and delay sleep, while journaling about completed activities should not trigger worry. The alternative hypothesis is that writing a to-do list will ‘offload’ those thoughts and reduce worry.”
The team didn’t know which way it would go. That’s what made the experiment worth running.
Why the comparison group matters
Both groups wrote. Nobody went to bed without writing anything.
So the experiment can’t show whether the to-do list sped up sleep, whether writing about completed activities slowed it down, or both. The authors acknowledge this directly. What the data show is narrower: if you’re writing about tasks at bedtime, upcoming ones were linked to faster sleep than finished ones.
That design was a choice, not an oversight. The researchers argued that a “no writing” group invites placebo effects, so they had both groups write about the same kind of content and changed only whether it pointed forwards or backwards in time.
It also differs from a University of Tokyo study that compared paper notebooks with tablets and smartphones for remembering appointments. The Baylor experiment didn’t pit paper against screens. Everyone wrote by hand; only the content changed.
Offloading is an idea, not a measurement
The intuitive explanation is offloading. When a task exists only in your head, you may feel a need to keep rehearsing it so it doesn’t slip away. Picture someone in bed reminding themselves, again and again, to book an appointment after breakfast. Once that reminder is on paper, there may be less reason to keep repeating it.
It’s plausible, but the study didn’t test it. The researchers didn’t measure worry after the writing task, and they say the mechanism “requires additional investigation”.
What “more specific” actually meant
You may have read that people who wrote more specific to-do lists fell asleep even faster. In the paper, “list specificity” meant the number of items written. Within the to-do group, people who listed more tasks tended to fall asleep sooner.
But nobody was assigned a long or short list, so this is a correlation, not proof that adding items speeds up sleep. And it was about the count of items, not their detail. It doesn’t mean every entry needs a deadline, a priority and an action plan.
Trying it yourself
The tested version is simple. Shortly before bed, spend five minutes writing down what you need to do over the next few days, in bullet points or sentences, and keep going for the full five minutes even if the list feels short.
One step goes beyond what the study tested, so treat it as a practical extra rather than a finding: put the list where you’ll see it in the morning, then leave it alone.
Keep the limits in view. This was a single night, participants’ first in the lab, with healthy young adults. It didn’t show that the effect lasts over weeks at home, and it didn’t test people with insomnia, which the authors flag as the next step. For persistent sleep problems, writing down worries away from bed is a technique often used within cognitive behavioural therapy for insomnia, which has a far deeper evidence base than a single experiment.
The finding leaves an intriguing possibility: putting tomorrow’s tasks on paper may make them easier to leave until morning. In this experiment, the to-do list group fell asleep sooner than the completed-activities group. Whether reduced worry explains that difference remains an open question.
