# What are circadian rhythms and their relationship to sleep? Circadian rhythms are the natural, internal processes that regulate the sleep-wake cycle and other behaviours in our bodies. The term "circadian" comes from the Latin words "circa" (meaning "around") and "diem" (meaning "day"), so it refers to processes that occur around a 24-hour day cycle. There is a strong relationship between circadian rhythms and sleep, as the body's natural sleep-wake cycle is regulated by the body's internal clock. Disruptions to this cycle, such as when people work night shifts or experience jet lag, can lead to sleep disorders and other health problems. There is also evidence that disruptions to the body's natural circadian rhythms may be linked to an increased risk of certain types of cancer. For example, research has shown that people who work night shifts or have irregular sleep patterns may have a higher risk of breast, prostate, and colon cancer. One theory is that disruptions to the body's natural circadian rhythms can disrupt the production of certain hormones, such as [melatonin](../3.%20Treatments/3.3%20%20Supplements/Melatonin.md), which have been shown to play a role in the development of cancer. So it's important to maintain a healthy sleep-wake cycle and to try to get enough sleep each night to help support the body's natural circadian rhythms. Strategies can include setting a consistent bedtime and wake-up time, creating a relaxing bedtime routine, and avoiding screens and other distractions before bed. # Matt's notes on sleep: Source research papers on the connection between sleep, circadian rhythms and cancer: