Jotting down tasks for the next day makes getting some shut eye easier and can combat difficulties dozing off, say experts.
Researcher compared sleep patterns of participants who took five minutes to write down forthcoming duties versus participants who chronicled completed activities.
Those who wrote a ‘to-do’ list found it easier to drop off to sleep than those who had listed tasks done all ready, psychologists found.
Study leader Professor Michael Scullin, of the sleep, neuroscience and cognition laboratory at Baylor University in Waco, Texas, said: “We live in a 24/7 culture in which our to-do lists seem to be constantly growing and causing us to worry about unfinished tasks at bedtime.
“Most people just cycle through their to-do lists in their heads, so we wanted to explore whether the act of writing them down could counteract nighttime difficulties with falling asleep.”
Some 40 percent of adults report difficulty falling asleep at least a few times each month, according to sleep experts.
The study of 57 university students was published in the American Psychological Association’s Journal of Experimental Psychology.
Prof Scullin said: “There are two schools of thought about this. 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.”
While anecdotal evidence exists that writing a bedtime list can help one fall asleep, the Baylor researchers used electrodes to monitor the electrical brain activity of volunteers.
Participants stayed in the lab on a week night to avoid weekend effects on bedtime and because on a weekday night, they probably had unfinished tasks to do the next day, Prof Scullin said.
They were divided into two randomly selected groups and given five-minute writing assignments before going to bed.
One group was asked to write down everything they needed to remember to do the next day or over the next few days.
The other group was asked to write about tasks completed during the previous few days. Study participants were told they could go to bed at 10.30 pm.
Prof Scullin said: “We had them in a controlled environment and absolutely restricted any technology, homework, etc. It was simply lights out after they got into bed.”
The researchers noted that while the sample size was appropriate for an experimental, laboratory-based study, a larger study would be useful in future.
Prof Scullin said: “Measures of personality, anxiety and depression might moderate the effects of writing on falling asleep, and that could be explored in an investigation with a larger sample.
“We recruited healthy young adults, so we don’t know whether our findings would apply to patients with insomnia, though some writing activities have previously been suggested to benefit such patients.”