yökierto

Yökierto is a Finnish term that translates to "night cycle" or "circadian rhythm." It refers to the natural, internal process that regulates the sleep-wake cycle of living organisms. This biological clock is influenced by light and darkness and plays a crucial role in maintaining various physiological functions, including hormone release, body temperature, and metabolism.

In humans, the night cycle is primarily regulated by the suprachiasmatic nucleus (SCN), a small region in the hypothalamus of the brain. The SCN receives light signals from the eyes, which help to synchronize the internal clock with the external environment. When it is dark, the SCN signals the pineal gland to produce melatonin, a hormone that promotes sleep. Conversely, when it is light, melatonin production is suppressed, leading to wakefulness.

Disruptions to the night cycle can have significant consequences for health and well-being. Factors such as irregular sleep schedules, shift work, jet lag, and excessive exposure to artificial light at night can all interfere with the natural rhythm. This can lead to sleep disorders, fatigue, impaired cognitive function, and an increased risk of chronic diseases like obesity, diabetes, and cardiovascular disease. Maintaining a consistent sleep schedule and minimizing exposure to disruptive light sources are important for promoting a healthy night cycle.