Pitt’s top licensed IP? A 35-year-old sleep research tool

Sleep still baffles parts of the scientific community, but innovations in how to study the subject have helped make steady progress ahead.

Much of the research today still relies on a decades-old foundation that started in Pittsburgh. 

In 1989, Daniel J. Buysse, fresh from his post-doctoral fellowship at the University of Pittsburgh, set out with his mentors to tackle a deceptively simple question: how can we measure sleep quality? 

Working with a team of other experts, the researchers developed the Pittsburgh Sleep Quality Index (PSQI) transforming sleep research and clinical practices worldwide. By 2024, over 34,000 peer-reviewed studies have cited the PSQI, cementing its role in sleep research.

Though PSQI is not necessarily the type of invention to spawn tech startups, its impact bolsters the local innovation ecosystem, especially as digital health and wearable tech evolve. It’s a foundation that pushes other sleep quality assessment ahead, and makes Pittsburgh a go-to place for this tech.

“The PSQI is a top-licensed IP at Pitt,” Buysse told Technical.ly. “It’s helped put Pittsburgh on the map in sleep research.”

Previously, sleep studies required lab setups that weren’t feasible for large-scale research, and the nuances of sleep disorders remained elusive. The PSQI includes a questionnaire measuring multiple aspects of sleep, from duration and efficiency to disruptions and daily impact.

By balancing subjective perceptions with measurable data, the researchers created a tool that could scale for global research. The result was a reliable, standardized measure of sleep quality that could differentiate patient groups and predict intervention effectiveness.

“One example I love,” Buysse said, “is that while sleep lab data shows older adults generally sleep worse than younger adults, PSQI results reveal that their self-reported sleep quality is quite similar. This discrepancy underscores a key insight: sleep perception and physiological data aren’t always in sync.” 

PSQI crosses cultural and research boundaries

The PSQI’s impact has been profound. Translated into 56 languages, it’s proven invaluable across a variety of contexts. 

“One of the great advantages of the PSQI is that it enables comparisons across cultures,” Buysse said. 

For example, translating “falling asleep,” which lacks a direct Spanish equivalent, taught him valuable lessons in cultural sensitivity. Such insights have only deepened the PSQI’s global influence, he said.

Insights like this, along with the PSQI’s comprehensive approach, have inspired new models like Multidimensional Sleep Health, which examines how sleep quality varies by age and cultural background.

The PSQI has also driven innovations in insomnia treatment. 

While it doesn’t prescribe treatment, its quantitative data lets clinicians track patient progress, evaluate intervention effectiveness, and make data-backed decisions. 

PSQI is now second only to polysomnography, which measures brain waves, oxygen levels, heart rate and breathing patterns during sleep, making the PSQI a less intrusive but still reliable tool for assessing insomnia.

35 years later, PSQI evolves in a tech-forward world 

Over time, Buysse and his team have adapted the PSQI for new clinical and research needs. 

One advancement, the Brief PSQI, condenses the questionnaire into six items, allowing quick but reliable assessments in larger studies or high-demand clinical settings. 

Developed with Spanish researchers, this shorter version retains the original tool’s rigor while enhancing accessibility — a crucial step as sleep research increasingly overlaps with digital health.

Wearables now allow insights into sleep and circadian rhythms through physiological data, like heart rate and sleep stages, that the PSQI, as a self-report measure, can’t capture. 

However, Buysse said the subjective insights from the PSQI will remain crucial. Only a self-report tool can capture the subjective experience of sleep quality — a “degree of excellence” that no physiological measure can replicate, he said.

“There’s incredible work going into measuring circadian rhythms and sleep physiology with wearables,” Buysse said. “But what’s powerful about the PSQI is that it tells us not only what the body is doing during sleep but also how a person feels about their sleep.”