Why some adults fall asleep and wake up much later than usual (delayed sleep‑wake timing)
Official title: Physiological and Behavioral Basis of Circadian Rhythm Delayed Sleep-Wake Phase Disorder
Funded at Northwestern University · NIH-11193826 · Data updated 2026-11-12
Researchers are comparing biological and behavioral differences in adults who fall asleep and wake up much later than typical to help tailor better diagnoses and treatments.
Quick facts
| Grant type | R01 grant |
|---|---|
| Study type | NIH-funded research |
| Funding institution | Northwestern University NIH-funded |
| Lab location | 1 site (Chicago, United States) |
| Project start | September 17, 2024 |
| Project end | July 31, 2029 |
| Funding year | 2025 |
| Award (this year) | $618,641 |
| NIH project number | 5R01HL174661-02 |
| Project ID | NIH-11193826 on NIH RePORTER |
Who could benefit from this research
✓Could help
Adults (about 21 years and older) who have trouble falling asleep at night and waking at typical times due to a late sleep schedule are ideal candidates.
✕Less likely to help
People whose sleep problems are caused by unrelated conditions (for example untreated sleep apnea, medication effects, or primary insomnia) or who are under 21 may not benefit directly from this study.
What this research studies
If you join, you would be asked about your sleep habits and come to Northwestern for tests that measure your body clock and how your eyes and brain respond to light. The team will group people into different types—those whose internal circadian clock is delayed and those whose sleep timing is delayed for other reasons—and measure differences like light sensitivity using pupillometry and other biological markers. The goal is to link measurable physiological differences with sleep behaviors so future care can be more personalized. Visits will likely include in-person assessments in Chicago and may involve sleep timing logs or wearable monitoring.
Why it matters
Potential benefit: This work could lead to clearer diagnoses and more personalized treatments that better match why your sleep timing is late.
How similar studies have gone: Earlier research, including the team's pupillometry work, has already found distinct subtypes and light‑sensitivity differences, but personalized treatments based on these findings are still largely untested.
Where this research is happening
-
Northwestern University
Chicago, United States Active
Researchers
- Principal investigator: Zee, Phyllis C. — Northwestern University
- Study coordinator: Zee, Phyllis C.
Related research
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A study at Northwestern University is exploring why some people with delayed sleep patterns have different light sensitivity and how this affects their sleep timing, with the goal of personalizing treatment for those with DSWPD.
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About this research
- This is an active NIH-funded research project — typically early-stage science, not a clinical trial accepting patient enrollment.
- Some NIH-funded labs run parallel clinical studies or seek volunteers for related work. To check, contact the principal investigator or institution listed above.
- For full project details, budget, and progress reports, visit the official NIH RePORTER page.