Measures of personality, anxiety and depression might moderate the effects of writing on falling asleep.
Having trouble falling asleep? Jotting down your "to-do" list just before bedtime can help you doze off quickly, scientists say.
Researchers from Baylor University in the US compared sleep patterns of participants who took five minutes to write down upcoming duties versus those who chronicled completed activities.
"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," said Michael K Scullin, assistant professor at Baylor University.
"Most people just cycle through their to-do lists in their heads, and so we wanted to explore whether the act of writing them down could counteract night time difficulties with falling asleep," said Scullin, lead author of the study Journal of Experimental Psychology.
While anecdotal evidence exists that writing a bedtime list can help one fall asleep, the study used overnight polysomnography, the "gold standard" of sleep measurement, Scullin said.
For the study 57 university students, participants stayed in the lab on a weeknight to avoid weekend effects on bedtime and because on a weekday night, they probably had unfinished tasks to do the next day, Scullin said.
They were divided into two randomly selected groups and given five-minute writing assignments before retiring.
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 to write about tasks completed during the previous few days. Students were instructed they could go to bed at 10:30 pm.
"We absolutely restricted any technology, homework, etc. It was simply lights out after they got into bed," Scullin said.
While the sample size was appropriate for an experimental, laboratory-based study, a larger future study would be of value, researchers 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," he said.
"We recruited healthy young adults, and so we don't know whether our findings would generalise to patients with insomnia, though some writing activities have previously been suggested to benefit such patients," he added.