A new study from researchers in Australia provides some of the most powerful evidence to date about the worldwide problem of inconsistent sleep. 

After evaluating months of sleep tracker data from a large group of participants, the study found that only 15% of participants slept 7-9 hours on 5 or more nights per week. Even worse, only 2% of people did so on 6 or more nights per week.

It’s well-known that many adults struggle to get the recommended amount of nightly sleep and that about one-third of Americans report getting less than 7 hours of sleep per night. So, it might be easy to overlook the results of this research published last month in the journal Sleep Health. But, the study merits attention both for its methodology and concerning findings about insufficient and inconsistent sleep.

Unlike other research based on questionnaires and sleep diaries, which are subject to participants’ spotty memory and incomplete or inaccurate entries, this study measured sleep time with under-the-mattress sleep trackers. Data was collected for roughly 9 months from over 68,000 adults in more than 20 countries, giving the study a greater scope and more objective data than most prior research. 

The researchers found major variations in the amount of time participants slept from night to night. Only a tiny subset of people slept for 7-9 hours every night of the week. While around two-thirds of study participants had an average sleep time within the recommended range, they still spent multiple nights every week sleeping either too much or too little. 

What explains this wild inconsistency in nightly sleep times? An important factor appears to be the difference between how long people sleep on weekdays and weekends. 

On average, study participants slept nearly a half-hour more on weekends. This suggests that many individuals cut their sleep short on weeknights and then try to “catch up” over the weekend. Sleep experts sometimes refer to this as “social jetlag.” It occurs when sleep schedules are disrupted during the week due to work or school obligations, and weekends and days off usually allow longer sleep.

“Clearly, getting the recommended sleep duration range frequently is a challenge for many people to achieve, especially during the working week,” says  Hannah Scott, Ph.D., the study’s lead author and a researcher at Flinders University in Australia.

Although the study provides compelling evidence, it does have limitations. It included a disproportionate number of males and people with excess weight, making it an inexact representation of the general population. It was conducted during the COVID-19 pandemic, which worsened sleeping difficulties. Also, readings from the sleep trackers could have been affected by bed partners and pets. 

Nevertheless, given the large sample size and consecutive months of tracker data, this research points to pervasive problems relating to the duration and regularity of sleep for countless adults around the globe. The findings are troubling since insufficient, excessive, and inconsistent sleep are associated with many health issues, including heart disease, diabetes, and obesity. 

“Given what we know about the importance of sleep to health, we also need to assist people to resolve chronic sleep difficulties and encourage all people to make sleep a priority,” says co-author Danny Eckert, Ph.D., a professor at Flinders University.

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4 Sources

  1. Scott, H., Naik, G., Lechat, B., Manners, J., Fitton, J., Nguyen, D. P., Hudson, A. L., Reynolds, A. C., Sweetman, A., Escourrou, P., Catcheside, P., & Eckert, D. J. (2024). Are we getting enough sleep? Frequent irregular sleep found in an analysis of over 11 million nights of objective in-home sleep data. Sleep Health, 10(1), 91–97.

  2. Consensus Conference Panel, Watson, N. F., Badr, M. S., Belenky, G., Bliwise, D. L., Buxton, O. M., Buysse, D., Dinges, D. F., Gangwisch, J., Grandner, M. A., Kushida, C., Malhotra, R. K., Martin, J. L., Patel, S. R., Quan, S. F., Tasali, E., Non-Participating Observers, Twery, M., Croft, J. B., Maher, E., … Heald, J. L. (2015). Recommended amount of sleep for a healthy adult: A joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Journal of Clinical Sleep Medicine, 11(6), 591–592.

  3. National Center for Chronic Disease Prevention and Health Promotion, Division of Population Health. (2022, November 2). Sleep and sleep disorders: Adults. Centers for Disease Control and Prevention., Retrieved March 4, 2004, from

  4. Flinders University. (2024, February 28). Wake-up call for better sleep., Retrieved March 4, 2024, from


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