You might have noticed thatyou feel energized or sleepy at the same times every day. You circadian rhythm is the reason why. In the sleep context, the circadian rhythm is your internal clock which controls when you are alert and tired. Circadian rhythms have been observed in plants and animals as well.
A biological rhythm must meet some criteria to be considered circadian. It has to be endogenous (self-sustained), and last approximately 24 hours, even in constant conditions. It can also be reset by external cues. A good example is when you travel to a different time zone.
Adults usually have their lowest energy levels in the middle of the night. The exact time can vary depending on your sleep chronotype. Night owls have peak energy at different times compared to morning persons. The existence of an internal clock is more evident for shift workers and when you experience jet lag. Even the biannual hour shift can disrupt our cycle.
Besides the natural variations for each person, our sleep cycle and sleep needs also change during the course of life:
Humans are diurnal animals, we live during the day and sleep at night. This is reflected in our circadian rhythm.Our sleep is heavily defined by the release of melatonin, also known as sleep hormone. This hormone is released during the evening, reaching its peak level at the middle of night, and decreasing to very low levels at the moment to wake up.
Light exposure is the most widely-known factor impacting our circadian rhythm but several others exist, such as temperature.
The disruption of this mechanism is linked to a number of disorders, such as bipolar disorder and delayed sleep phase disorder. It also believed to have long-term adverse effects on peripheral organs, especially the development of cardiovascular diseases.
Obesity and diabetes are associated with both genetic and lifestyle factors. Amongst them, disruptions in the sleep cycle might play a role in the development of metabolic disorders. Irregular eating times is associated with insulin sensitivity and higher body mass, which may lead to cardiovascular and hypertension in the long-term, reducing the life expectancy.
We also have some tips to help you regulate and maintain an healthy circadian cycle: