Circadian cycle for night shift workers

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A circadian cycle (also called circadian rhythm) is a set of physical and mental changes that occur in our body over an approximate 24-hour period (circa = about; dian = a day).

It is responsible for regulating important functions in your body, such as:

• Sleep schedule
• Appetite
• Body temperature
• Hormone levels
• Blood pressure

In practice, an uninterrupted cycle would work roughly like this:

Keep in mind that each person has a cycle that varies slightly in timing, and the image above is just an example, okay?

As you can see, the biological clock regulates many functions. Today we'll focus on sleep schedule

Regardless of learned routines, lifestyle, and/or social context, each individual has their own circadian cycle, which varies slightly in its start time. This means that even identical twins can have completely different biological clocks. That's why some people like to sleep and wake up early (called morning types) while others prefer to sleep and wake up later (called evening or night types).

From the brain and body's perspective, humans are designed to sleep at night—otherwise, we would have adaptations like night vision, and enhanced smell and hearing like nocturnal animals.

This is why night shift work, for example, directly impacts the circadian cycle. When workers leave their workplace needing to rest so their body can perform all the necessary maintenance during a night's sleep, they encounter sunlight, which naturally keeps their body in an alert state.

Beyond the impact on functions regulated by the circadian cycle, there's also a consequence in the workplace itself: errors and accidents. Some of the world's most significant human errors occurred during night shift work, such as the Chernobyl disaster and the Three Mile Island accident.

But don't worry!

There are, of course, tools that can help you rest better and avoid serious health problems. One example is using light to your advantage, as it's one of the main factors that impacts the circadian cycle. The darker and quieter a place is, the more your brain will understand that it's time to rest. And the opposite is also true: the brighter the environment, the more alert your body will be.