Going beyond the limits: effect of clock disruption on human health

Abstract

Synchronisation of organisms’ physiology and behaviour with the external environment is necessary for survival and reproductive fitness. This is critical for human health also. In the past, humans were exposed to predictable natural day and night cycles that allowed the internal clock to synchronise the daily rhythms in physiology and behaviour with the external environment. However, the industrial revolution has made us a 24*7 society and forced the extension of day into night via adoption of artificial light in our lives. This has altered the perception of day and night and made it difficult for the biological processes to synchronise. Such weak synchronisation can be seen in different physiological and behavioural functions that are under circadian control, such as sleep–wake behaviour, melatonin and cortisol rhythms, core body temperature cycle, etc. This also influences the regulatory mechanism at cell and gene levels. Circadian disruption has resulted in increasing incidences of certain cancers, metabolic dysfunction and mood disorders. Several evidence suggest that exposure to aberrant light alters the brain functions that regulate emotion and mood. The present discussion focuses on understanding the effect of circadian disruption on human health, and its various aspects.

Keywords:

• Circadian disruption
• health
• mood disorders
• rhythm
• sleep-wake behaviour