Lockley's research focuses on basic and applied aspects of human circadian biology, using epidemiology, field-based physiological studies, and inpatient intensive physiological monitoring. He has a particular interest in human circadian photoreception and the effects of light on the circadian pacemaker and other non-image forming responses. Lockley's studies include investigations of the effects of timing, duration, intensity and wavelength of light exposure on circadian resetting, melatonin suppression, and the acute alerting effects of light.