Working night shifts has been identified as a potential risk factor for developing certain types of cancer, primarily due to the disruption of the body's natural circadian rhythm and the suppression of melatonin production. The International Agency for Research on Cancer (IARC) has classified night shift work as a 'probable carcinogen' (Group 2A) [2, 8, 14, 30]. This classification is based on evidence suggesting a link between night shift work and an increased risk of breast, prostate, and colorectal cancers [4, 9, 14, 30]. Some studies have indicated a higher risk for women, with a meta-analysis finding that long-term night shift work increased the risk of cancer by 19% in women, and specific increased risks for breast, skin, and gastrointestinal cancers [3, 20]. For instance, among female nurses, night shift work was associated with a 58% increased risk of breast cancer, a 35% increased risk of gastrointestinal cancer, and a 28% increased risk of lung cancer [3]. The mechanism involves exposure to light at night, which reduces melatonin secretion. Melatonin is a hormone that helps regulate sleep and has oncostatic (cancer-suppressing) properties [7, 12, 24]. Its suppression can lead to increased oxidative damage and hormonal imbalances, creating an environment more conducive to cancer development [7, 24]. Circadian rhythm disruption can also affect DNA repair mechanisms, making cells more vulnerable to damage [23, 29]. However, the evidence is not entirely conclusive. Some recent meta-analyses combining data from numerous studies have found no significant overall association between night shift work and the risk of various cancers, including breast, prostate, and colorectal cancers [5]. It's also noted that other factors, such as obesity, physical activity, and diet, can indirectly contribute to the increased health risks associated with night shift work [2, 32]. The relevance to India is significant, given its large workforce in sectors that operate round-the-clock, including BPO, healthcare, and manufacturing.