What are Circadian Rhythms?

The circadian rhythm refers to the change of life activity with a period of about 24 hours. Also known as the recent rhythm. Luminescent bacteria glow, plant photosynthesis, animal feeding, physical activity, sleep and wakefulness show circadian rhythms. There are also obvious circadian fluctuations in human physiological functions, learning and memory abilities, emotions, and work efficiency. Circadian rhythm is closely related to human activities. Disturbance of the circadian rhythm will lead to decreased appetite, decreased work efficiency, and increased accidents; different drug administration times will have different effects; different effects of toxicants will have different toxicity manifestations; and the sensitivity of tumor cells to X-rays will also vary between day and night . In general, human vitality is lowest at midnight.

circadian rhythm

The various physiological functions of living organisms can establish a regular cycle that adapts to the diurnal changes of the external environment. Both the natural world and the biological world have their own rigorous rhythms. Human

A person flying from a time zone to another time zone by jet on a long-distance transcontinental flight, and his

The circadian rhythm of space flight is different from the circadian rhythm on earth. Its period is related to the orbit of the spacecraft. The high orbit period is long and the low orbit period is short. The manned spacecraft in low-Earth orbit has an orbital period of about 90 minutes, which means that the diurnal cycle is 90 minutes, and there are 16 diurnal changes in 24 hours. Days and nights have different lengths of time. Days are long and nights are short. The spacecraft flies in the sunny area of the earth during the day and night in the shadowed area of the earth. The change of circadian rhythm in space has a certain impact on the physiological functions of astronauts. In the early stage of manned spaceflight, astronauts did not adapt to the new living system and did not sleep well. After returning to the ground, they also experienced sleep disorders. In modern manned spaceflight, it is necessary to make scientific arrangements for the astronauts' rest time and maintain the living habits and circadian rhythms on the ground. The light arrangement of the spacecraft is used to simulate the day and night brightness changes on the earth, so that the astronauts can adapt to the new environment and maintain normal working ability.