Night time

Night time, often referred to simply as night, is the period of time from sunset to sunrise in each twenty-four hours, when the Sun is below the horizon. This period is characterized by darkness, which occurs due to the Earth's rotation blocking sunlight from reaching a particular part of the planet. The concept of night time is significant in various aspects of culture, biology, astronomy, and psychology, influencing countless natural processes and human activities.

Characteristics

Night time is marked by a decrease in light levels, leading to a natural transition from daylight to twilight and eventually to darkness. This change influences the behavior of many organisms, including humans, by signaling the end of daily activities for some and the beginning of activities for nocturnal species. The temperature also typically drops during the night due to the absence of sunlight, affecting weather and climate patterns.

Astronomical Perspective

In astronomy, night time is a fundamental concept, dividing the Earth's rotation into day and night cycles. The start and end of night are defined by astronomical events: sunset, when the Sun's disk moves below the horizon, and sunrise, when it moves back above the horizon. The duration of night varies depending on the location's latitude and the time of year, with longer nights in the winter and shorter ones in the summer for each hemisphere.

Biological Impacts

The transition to night triggers significant changes in the behavior and physiology of living organisms, a phenomenon known as circadian rhythms. These internal biological clocks help organisms adapt to the regular rhythm of day and night. In humans, exposure to darkness at night influences the production of melatonin, a hormone that promotes sleep and regulates sleep-wake cycles.

Cultural and Social Aspects

Throughout history, night time has been a source of inspiration and mystery in various cultures, influencing literature, art, and mythology. It has been associated with both fear and fascination, giving rise to stories of nocturnal creatures and moonlit adventures. In modern societies, night time is also a period for certain social activities and industries, such as nightlife and astronomy.

Environmental Concerns

The advent of artificial lighting has significantly altered natural night time environments, leading to light pollution. This phenomenon not only obscures the night sky, making it difficult to observe celestial bodies, but also disrupts the natural behaviors of nocturnal wildlife and affects human health by interfering with natural circadian rhythms.

See Also

• Circadian rhythm
• Daylight
• Light pollution
• Sunset
• Sunrise

Night time Resources
Latest articles Most recent articles Ongoing trials	Wikipedia