Steven W. Lockley, Ph.D.

Co-founder & Chief Scientist

Dr. Steven Lockley is the Co-founder and Chief Scientist at Timeshifter. Before joining Timeshifter full-time in 2024, he served as a Neuroscientist at Brigham and Women’s Hospital and as an Associate Professor of Medicine in the Division of Sleep Medicine at Harvard Medical School, where he was on the faculty for over 20 years. With nearly three decades of research experience, Dr. Lockley is a globally recognized authority on circadian rhythms and sleep. He has helped numerous organizations and individuals manage jet lag, shift work disorder, and optimize performance. Dr. Lockley has applied his expertise to guide NASA astronauts and mission controllers, Formula 1 drivers, and elite athletes.

Dr. Lockley is a world-renowned specialist in ways to reset the circadian clock using light or melatonin and its agonists, the only known ways to phase shift circadian rhythms in humans. He has studied the effects of light on the circadian pacemaker extensively including the role of light wavelength, timing, duration and pattern. This work has led to development of ‘smart’ lighting applications designed to improve alertness, safety and productivity in architectural and clinical applications, and he was one of the leading scientists in the development and application of new lighting systems for the International Space Station.

Dr. Lockley has also made major discoveries in the use of melatonin and its agonists to reset circadian rhythms. He was the first person to show that daily melatonin treatment could synchronize the circadian clock of blind people suffering from non-24-hour sleep-wake disorder, which inspired the development of tasimelteon (Hetlioz) for use as a circadian synchronizer in the blind. Dr Lockley led the resulting clinical trials, and tasimelteon was approved by the FDA as the world’s first drug in a new class of therapies that treat circadian sleep disorders by resetting the circadian clock.

Dr. Lockley has also extensive experience in studying shiftwork and how to manage it. He has led multiple trials to test interventions to reduce workplace errors and injury, and to measure the impact of circadian disruption, long work hours, sleepiness and sleep disorders on performance and health, including in doctors, nurses, police,firefighters, and industry. His clinical trials have been able to demonstrate a significant impact in important real-world outcomes, including reducing medical errors by 30-36% in US and UK doctors; a 33% reduction in serious medical errors in ICU nurses; a 47% reduction in long-term disability days in firefighters, and a 43% reduction in falls in care home residents.

Dr. Lockley is a highly productive scientist, and has published over 200 original scientific papers, reports, reviews, chapters and editorials, as well as co-editing the first textbook on sleep and health ‘Sleep, health and society: From Aetiology to Public Health’ and co-authoring ‘Sleep: A Very Short Introduction’ from Oxford University Press. His work has been widely reported in numerous press articles including in National Geographic, Time magazine, BBC, New York Times, Wall Street Journal, Financial Times, New Yorker, Scientific American and many others. His research has been funded by NASA and the National Institutes of Health (NIH) among others andhe has won a number of awards including the NASA Johnston Space Center Director's Innovation Team Award (as part of the ISS Flexible Lighting Team).

Articles

Publications

Exploring the associations between shift work disorder, depression, anxiety and sick leave taken amongst nurses.

Authors: Booker LA, Sletten TL, Alvaro PK, Barnes M, Collins A, Chai-Coetzer CL, Naqvi A, McMahon M, Lockley SW, Rajaratnam SMW, Howard ME.
J Sleep Res 2020-06-01
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Manipulating sleep duration perception changes cognitive performance - An exploratory analysis.

Authors: Rahman SA, Rood D, Trent N, Solet J, Langer EJ, Lockley SW.
J Psychosom Res 2020-05-01
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Journal of Pineal Research guideline for authors: Measuring melatonin in humans.

Authors: Lockley SW.
J Pineal Res 2020-04-28
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The role of sleep hygiene in the risk of Shift Work Disorder in nurses.

Authors: Booker LA, Barnes M, Alvaro P, Collins A, Chai-Coetzer CL, McMahon M, Lockley SW, Rajaratnam SMW, Howard ME, Sletten TL.
Sleep 2020-02-13
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Menstrual phase-dependent differences in neurobehavioral performance: the role of temperature and the progesterone/estradiol ratio.

Authors: Grant LK, Gooley JJ, St Hilaire MA, Rajaratnam SMW, Brainard GC, Czeisler CA, Lockley SW, Rahman SA.
Sleep 2020-02-13
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Characterizing the temporal Dynamics of Melatonin and Cortisol Changes in Response to Nocturnal Light Exposure.

Authors: Rahman SA, Wright KP, Lockley SW, Czeisler CA, Gronfier C.
Sci Rep 2019-12-23
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Light Me up? Why, When, and How Much Light We Need.

Authors: Vetter C, Phillips AJK, Silva A, Lockley SW, Glickman G.
J Biol Rhythms 2019-12-01
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Associations between sleep disturbances, mental health outcomes and burnout in firefighters, and the mediating role of sleep during overnight work: A cross-sectional study.

Authors: Wolkow AP, Barger LK, O'Brien CS, Sullivan JP, Qadri S, Lockley SW, Czeisler CA, Rajaratnam SMW.
J Sleep Res 2019-12-01
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Endogenous Circadian Regulation of Female Reproductive Hormones.

Authors: Rahman SA, Grant LK, Gooley JJ, Rajaratnam SMW, Czeisler CA, Lockley SW.
J Clin Endocrinol Metab 2019-12-01
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Associations between shift work characteristics, shift work schedules, sleep and burnout in North American police officers: a cross-sectional study.

Authors: Peterson SA, Wolkow AP, Lockley SW, O'Brien CS, Qadri S, Sullivan JP, Czeisler CA, Rajaratnam SMW, Barger LK.
BMJ Open 2019-12-01
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Using a Single Daytime Performance Test to Identify Most Individuals at High-Risk for Performance Impairment during Extended Wake.

Authors: St Hilaire MA, Kristal BS, Rahman SA, Sullivan JP, Quackenbush J, Duffy JF, Barger LK, Gooley JJ, Czeisler CA, Lockley SW.
Sci Rep 2019-11-13
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Classifying attentional vulnerability to total sleep deprivation using baseline features of Psychomotor Vigilance Test performance.

Authors: Chua EC, Sullivan JP, Duffy JF, Klerman EB, Lockley SW, Kristal BS, Czeisler CA, Gooley JJ.
Sci Rep 2019-08-20
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Effects on resident work hours, sleep duration, and work experience in a randomized order safety trial evaluating resident-physician schedules (ROSTERS).

Authors: Barger LK, Sullivan JP, Blackwell T, O'Brien CS, St Hilaire MA, Rahman SA, Phillips AJK, Qadri S, Wright KP, Segar JL, McGuire JK, Vitiello MV, de la Iglesia HO, Poynter SE, Yu PL, Zee P, Sanderson AL, Halbower AC, Lockley SW, Landrigan CP, Stone KL, Czeisler CA.
Sleep 2019-08-01
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Application of a Limit-Cycle Oscillator Model for Prediction of Circadian Phase in Rotating Night Shift Workers.

Authors: Stone JE, Aubert XL, Maass H, Phillips AJK, Magee M, Howard ME, Lockley SW, Rajaratnam SMW, Sletten TL.
Sci Rep 2019-07-30
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Generalizability of A Neural Network Model for Circadian Phase Prediction in Real-World Conditions.

Authors: Stone JE, Phillips AJK, Ftouni S, Magee M, Howard M, Lockley SW, Sletten TL, Anderson C, Rajaratnam SMW, Postnova S.
Sci Rep 2019-07-29
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How to Report Light Exposure in Human Chronobiology and Sleep Research Experiments.

Authors: Spitschan M, Stefani O, Blattner P, Gronfier C, Lockley SW, Lucas RJ.
Clocks Sleep 2019-07-01
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Shift Work, Chronotype, and Melatonin Rhythm in Nurses.

Authors: Razavi P, Devore EE, Bajaj A, Lockley SW, Figueiro MG, Ricchiuti V, Gauderman WJ, Hankinson SE, Willett WC, Schernhammer ES.
Cancer Epidemiol Biomarkers Prev 2019-07-01
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Sleepiness and driving events in shift workers: the impact of circadian and homeostatic factors.

Authors: Mulhall MD, Sletten TL, Magee M, Stone JE, Ganesan S, Collins A, Anderson C, Lockley SW, Howard ME, Rajaratnam SMW.
Sleep 2019-06-11
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High sensitivity and interindividual variability in the response of the human circadian system to evening light.

Authors: Phillips AJK, Vidafar P, Burns AC, McGlashan EM, Anderson C, Rajaratnam SMW, Lockley SW, Cain SW.
Proc Natl Acad Sci U S A 2019-06-11
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Sleep regularity is associated with sleep-wake and circadian timing, and mediates daytime function in Delayed Sleep-Wake Phase Disorder.

Authors: Murray JM, Phillips AJK, Magee M, Sletten TL, Gordon C, Lovato N, Bei B, Bartlett DJ, Kennaway DJ, Lack LC, Grunstein RR, Lockley SW, Rajaratnam SMW.
Sleep Med 2019-06-01
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