I always wondered why people must sleep at night. Sleep is an essential part of our daily lives. Getting enough quality sleep at night is crucial for our physical and mental well-being.

One of the primary reasons why people must sleep at night is to allow the body to repair and restore itself. During sleep, our bodies undergo several restorative processes that help repair tissues, boost the immune system, and improve brain function. For instance, while we sleep, the body releases growth hormones, which play a crucial role in repairing damaged tissues, building muscle mass, and strengthening bones.

Sleep also plays a critical role in maintaining our cognitive function. It helps consolidate our memories and information learned during the day, which enhances our ability to learn and retain new information. Studies have also shown that people who get enough sleep at night have better problem-solving and decision-making abilities and are generally more productive.

Another reason why people must sleep at night is to regulate their emotions. A lack of sleep can affect our moods and emotional responses, leading to irritability, anxiety, and even depression. Sleep deprivation can make it difficult for individuals to regulate their emotions, making them more prone to impulsive behaviour.

Getting enough sleep at night is crucial for maintaining a healthy weight. Lack of sleep can affect the body’s metabolism, leading to an increased appetite and weight gain. Studies have shown that people who sleep less than seven hours per night are more likely to be overweight or obese.

But why must people sleep at night, not during the daytime?

The human body has an internal biological clock known as the circadian rhythm. This internal clock regulates various physiological processes, including sleep-wake cycles. Circadian rhythm is primarily controlled by the release of the hormone melatonin, produced by the brain’s pineal gland. Melatonin levels rise in the evening, signalling to the body that it is time to sleep, and decrease in the morning, signalling to the body that it is time to wake up.

Because the circadian rhythm is regulated by external factors such as light and darkness, most people tend to feel more alert and awake during the day and sleepy at night. This is why sleeping at night is considered more natural and beneficial for our health and well-being.

While it is possible to sleep during the day, doing so may disrupt the circadian rhythm and lead to sleep disturbances or other health issues. For example, shift workers who are required to work overnight may experience disruptions in their sleep-wake cycles, leading to an increased risk for obesity, diabetes, and other health problems.