Does writing down worries before bed help sleep?

What happens when you write before bed?

Bedtime worry is a known contributor to difficulty falling asleep, and worrying about incomplete future tasks is a significant part of that¹. The idea that writing things down helps is popular, but most bedtime-routine advice treats it as intuitive rather than tested. The research is thinner than you might expect, and the strongest test suggests that what you write matters more than the act of writing itself.

The to-do list study: what actually happened

The clearest evidence comes from a 2018 randomised controlled trial by Scullin and colleagues¹. Fifty-seven healthy young adults aged 18 to 30 spent a night in a controlled sleep laboratory with polysomnography monitoring. Before bed, they were randomly assigned to one of two five-minute writing tasks.

One group wrote a to-do list of tasks they needed to remember to complete over the next few days. The other group wrote about tasks they had completed over the previous few days.

The result: participants in the to-do list condition fell asleep significantly faster than those in the completed-list condition¹. The effect also scaled with specificity. The more specifically participants wrote their to-do list, the faster they subsequently fell asleep. For completed activities, the trend ran in the opposite direction¹.

This is the only study in the provided evidence that directly measured sleep onset latency with polysomnography while testing bedtime writing. It suggests that offloading future tasks, in detail, may reduce the mental work of holding those tasks in mind.

What about writing worries and emotions?

Two older trials tested a different approach: Pennebaker-style writing, which asks people to write about thoughts, worries and emotions to promote emotional processing.

In a 2009 randomised controlled trial, 28 people with primary insomnia were randomised to three nights of Pennebaker writing or a control condition after a one-night baseline². Writing significantly reduced pre-sleep cognitive arousal on one of two measures, but it did not significantly reduce sleep onset latency². In other words, the writing changed something psychological, but not the measured time to fall asleep.

A 2003 pilot study with 42 poor sleepers tested three conditions across three nights: writing about worries and concerns with an emphasis on emotional expression, writing about hobbies as a distraction, or no writing³. The "problems" writing group reported shorter sleep onset latency than the no-writing group³. However, this was a pilot study using self-reported sleep onset, not a lab measure, so the evidence is weaker.

Taken together, the emotional-writing evidence is mixed. It may reduce cognitive arousal, but the only polysomnographic trial found no significant effect on sleep onset latency². The pilot study suggests a possible benefit, but it needs replication with objective measures.

Why a to-do list might work differently

The to-do list finding fits a plausible mechanism: incomplete tasks create mental load. Writing them down externally may reduce the need to keep rehearsing them mentally. The Scullin study found that specificity predicted faster sleep onset, which is consistent with the idea that a detailed list captures more of the task's mental load¹.

This is not the same as emotional processing. A to-do list is about externalising future demands; emotional writing is about processing past or present feelings. The evidence suggests these are different interventions with different effects on sleep.

How to try it yourself

If you want to test this, the protocol from the strongest study is simple: for five minutes before bed, write a specific to-do list of tasks you need to complete over the next few days¹. Be specific about each task rather than writing vague categories.

A plain notebook is all you need. A Leuchtturm1917 notebook has numbered pages and an index, which can help you keep lists organised. A Moleskine notebook with an elastic closure is a simple option for keeping by the bed. If you prefer structure, The Five Minute Journal has short evening prompts, though its focus is gratitude and intentions rather than task offloading.

Keep the writing short. The study used five minutes¹. There is no evidence in the provided sources that longer writing sessions improve sleep further.

What the research doesn't tell us

The strongest finding comes from healthy young adults in a single night in a sleep lab¹. We don't know from this study whether the effect holds for people with insomnia, older adults, or over many nights at home.

The emotional-writing trials used people with insomnia and poor sleepers, but their results were mixed and relied partly on self-report^2,3. None of the provided studies tested a combination of to-do lists and emotional writing.

If you have persistent difficulty sleeping that affects your daily life, that is worth discussing with a GP rather than treating writing as a fix.

Bottom line

The evidence is moderate for one specific practice: writing a specific to-do list for five minutes before bed may help healthy young adults fall asleep faster¹. The evidence for emotional writing as a sleep aid is limited and mixed^2,3. If you want to try something tonight, the to-do list is the better-supported option.