Shantha is Professor of Sleep and Circadian Medicine, Head of the School of Psychological Sciences and is Chair of the Monash Sleep Network. He is a Fellow of the Australian Academy of Health and Medical Sciences. Shantha leads the International Association of Circadian Health Clinics and co-leads Mentally Healthy Workplaces Australia (MHWA). 

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

Sleep is increasingly recognised as the third pillar of good health, along side diet and exercise. Poor sleep quality and sleep deficiency are linked to a number of serious health problems, including depression and cardiovascular disease, as well as impaired alertness and neurocognitive functioning, reduced productivity and increased accident risk.

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.

Sleep and ciradian health offer an opportunity to implement a preventive health approach that is grounded in neuroscience and strongly evidence based. This is based on the extensive evidenced that poor sleep and circadian health lead to other major adverse health and wellbeing outcomes, and interventions to improve sleep and circadian health are known to lead to improvements in overall health and wellbeing.