This is an invited research digest contributed by Dr. Hannah Ballard (Texas A&M University) and Dr. Michael K. Scullin (Baylor University).
Do you ever lie awake in bed at night waiting to fall asleep? If so, you are not alone: 40% of Americans report trouble falling asleep at night . Difficulty falling asleep is not only an American problem, but a global sleep “epidemic” . The problem is exacerbated by nighttime technology use, poor bedtime habits, and most importantly, worry and rumination. An emerging idea is that, at bedtime, people often worry about their incomplete tasks and anticipate future events. With work demands, people’s days have become increasingly busy, and 24/7 email access can make it difficult to disengage from work. The subsequent cognitive arousal then disrupts our ability to fall asleep. In our recent work, we explored a potential solution to bedtime worry: Writing about one’s worries can relieve rumination and allow the brain to rest.
Expressive writing has been demonstrated to benefit mental and physical health, and even academic success . But, the benefits of writing on sleep have received minimal attention. Therefore, we recruited 60 young adults to stay overnight in the Baylor University Sleep Neuroscience and Cognition Laboratory. Before bedtime, participants spent 5 minutes writing either a to-do list or a completed activity list . The to-do list required people to write about tasks that they needed to complete in the next few days whereas the completed activity list required that they write about tasks they had already completed in the past few days. To determine how long it took participants to fall asleep, we used polysomnography, which involves applying electrodes to record electrical activity from the scalp (brain waves).
One hypothesis was that writing about incomplete future tasks would aggravate the person’s focus on their worries and make it harder to fall asleep. The alternative hypothesis was that writing about unfinished tasks (to-do list), could curtail bedtime worry and reduce difficulty falling asleep. We found that participants who wrote a to-do list fell asleep, on average, 9 minutes faster than those who wrote a completed activity list. This finding was consistent with the view that writing about worrisome thoughts helps to “offload” those thoughts from consciousness .
We also observed that the number of to-do items that participants wrote correlated with the amount of time it took to fall asleep: The more detailed the list, the faster people fell asleep. As illustrated by Figure 1, participants who wrote 10 or more to-do list items fell asleep significantly faster than those who wrote fewer than 10 items, as well as participants who wrote 10 or more completed activity items. For practical purposes, it is important to recognize that writing a short to-do list yielded no benefits to sleep. Instead, the benefits of writing require some effort dedicated to writing everything that is on one’s list.
Figure 1. Writing a very specific to-do list (10 or more items) reduces the amount of time it takes to fall asleep. ns indicates p > .10 (not significant). Statistically significant comparisons are indicated by ** (p < .01) and *** (p < .001).
Even though it may seem that writing a to-do list might incite anxiety and cause bedtime worrying, we found that writing can allow the brain to relinquish future intentions and worries. Reducing difficulty falling asleep can help improve sleep quantity and quality, which contributes to the maintenance of cognitive functioning and physical health . While we found a benefit of writing for healthy individuals, future research needs to test the generalizability of this effect. Interestingly, Harvey and Farrell  observed that writing about one’s anxieties during the day could benefit participants with probable insomnia, and psychologists have long recommended that patients maintain a “worry list” . Building on this literature, our study suggests that the content and quantity of one’s writing matters. Individuals who have trouble falling asleep at night may benefit from spending 5 minutes before bedtime writing a very specific to-do list (Figure 2).
Figure 2. The below specific to-do list took the second author approximately 5 minutes to write.
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 Pennebaker, J. W., & Smyth, J. M. (2016). Opening up by writing it down: How expressive writing improves health and eases emotional pain. New York, NY: Guilford Press Publications.
 Scullin, M. K., Krueger, M., Ballard, H., Pruett, N., & Bliwise, D. L. (2018). The effects of bedtime writing on difficulty falling asleep: A polysomnographic study comparing to-do lists and completed activity lists. Journal of Experimental Psychology: General, 147, 139-146.
 Jansson-Fröjmark, M., Lind, M., & Sunnhed, R. (2012). Don’t worry, be constructive: A randomized controlled feasibility study comparing behavior therapy singly and combined with constructive worry for insomnia. British Journal of Clinical Psychology, 51, 142–157.
 Scullin, M. K., & Bliwise, D. L. (2015). Sleep, cognition, and normal aging: integrating a half century of multidisciplinary research. Perspectives on Psychological Science, 10(1), 97-137.
 Harvey, A. G., & Farrell, C. (2003). The efficacy of a Pennebaker-like writing intervention for poor sleepers. Behavioral Sleep Medicine, 1, 115–124.
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