Shantha is Professor of Sleep and Circadian Medicine, Head of the School of Psychological Sciences. He is Chair of the Sleep Health Foundation, and a Fellow of the Australian Academy of Health and Medical Sciences. He is Chair of the Monash Sleep Network.

His primary research interest is in the field of sleep and circadian rhythms, and its application to occupational and clinical settings.

Shantha's research program aims to investigate the role of the internal biological clock in the regulation of the sleep-wake cycle, and how disruption of the clock leads to sleep disorders and other physiological consequences (for example, in shift workers). His group is developing novel treatment approaches for sleep disorders that are caused by biological clock disruption. These include light and melatonin treatments. The group is also investigating the contribution of sleep disturbances and fatigue to mood disorders and impaired cognition in clinical populations.

Sleep loss and impaired alertness adversely affect occupational safety, health and productivity, and also road safety. About 20 percent of serious car crash injuries are associated with driver sleepiness. Shantha's research is examining innovative technologies to monitor alertness in occupational and transportations settings, and is developing and testing intervention strategies aimed at reducing the burden associated with impaired alertness in these contexts.