Measuring sleep de jour: how daily sleep diaries may provide sleep researchers an upper hand in data collection and analysis

How many hours did you sleep last night? Sounds like an easy question to answer, right? But for scientists who study sleep, getting accurate data is a real challenge. And without good data, researchers, as well as health and safety professionals, can’t provide the public with evidence-based recommendations or treatments.

Sleep affects almost everything, from your health to your mood to your risk of accidents.  So, sleep researchers need good ways to measure it.  A new report in the journal npj Biological Timing and Sleep, has provided evidence that one of the best tools to measure sleep may also be one of the easiest for study participants and researchers to use: a daily online diary. 

According to the research team, the most accurate way to measure sleep is called polysomnography, or PSG. PSG uses an array of sensors to record the body’s brain waves, breathing, heart rate, and movements while an individual sleeps. While the “gold standard,” PSG’s drawbacks include the expense of the equipment and the necessity for trained staff, which makes it challenging to use during long-duration studies with larger numbers of participants.

According to the study’s lead author, OccHealthSci’s Andrew McHill, Ph.D., other methods have issues as well. Tools like questionnaires have utility, but people’s memories can be fuzzy. Wearable devices are also an option for researchers; however, issues with compliance (wearing the devices) and technical factors like running out of power or mistaking stillness for sleep can corrupt data. Even paper diaries have issues—pages get lost, writing is hard to read, and simple mistakes can cause issues with the data.

Enter the eDiary. The research team tested their online sleep diary with 266 undergraduate college students for a month. Twice a day every day during the study, the students got an email link to log their sleep and activities. The eDiary transformed student entries into colorful charts that helped the students spot errors in their data entry. The system also sent reminders to the students who forgot to enter their data.

The results: student participation in the study under the eDiray system reached 95 percent and the research team experienced a dramatic reduction in time spent on data entry and analysis. Additionally, the research team found that compared with the eDiary, students who submitted survey responses or wore wearable sleep monitors overestimated their sleep.

“Overall, our findings suggest that eDiaries are a good and useful tool to measure multiple days of sleep timing, duration, and variability” said Associate Professor Andrew Mchill. “They also have the benefit of reducing the time we spend inputting and analyzing data for a large and geographically dispersed number of study participants.”

While the authors note the benefits of using an eDiary for sleep data collection, they also point to some limitations. An online diary needs internet access. Accurate data also depends on people being honest and careful with their entries.

Still, according to McHill, eDiaries could empower scientists to track the sleep of thousands of people at once, even across great distances. That could help uncover new links between how we sleep and how healthy we are. 

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McHill, A.W., St Hilaire, M.A., Sano, A. et al. Required components of a sleep-wake online daily diary for accurate and efficient human research. npj Biol Timing Sleep 3, 45 (2026). https://doi.org/10.1038/s44323-026-00106-z