Frequent sunrises and sunsets: the effects of spaceflight on astronauts' psychology and sleep

Wang Tao, Shi Tiejun, Bai Xiaojun, Gu Jianwen, Yang Yuan, Wang Yuan, Liu Xin, Strategic Support Force Characteristic Medical Center, Neurosurgery, Shenzhou Medical Team, Aerospace Clinical Medicine Department, Medical Research Department

Spaceflight is a challenging task that includes one of the factors that have an impact on the astronaut's psychology and sleep is the frequency of sunrises and sunsets. In space, astronauts may experience sunrises and sunsets multiple times a day, which can have an impact on their mental state and sleep quality.

In space flight, the speed at which the vehicle orbits the Earth determines how many sunrises and sunsets astronauts may experience per day. The exact number of times depends on the orbit and speed of the aircraft. For the International Space Station (ISS), its orbit around the Earth is about one circle every 90 minutes. This means that astronauts may experience about 16 sunrises and sunsets on the ISS, i.e. about 8 sunrises and 8 sunsets per day. This is due to the fact that every 90 minutes on the ISS, astronauts go from the shadow of the Earth to the sun-exposed area, and then again into the shadow. However, for other space missions, such as lunar missions or deep space exploration missions, the orbit and speed of the spacecraft may vary. This means that astronauts may experience fewer or more sunrises and sunsets. For example, an astronaut on a lunar mission may experience a lunar sunrise and a lunar sunset on the lunar surface, which is different from the number of sunrises and sunsets on Earth.

First, let's take a look at how astronauts experience multiple sunrises and sunsets during space flight. In space, spacecraft orbit the Earth at very high speeds, making multiple round-trips around the Earth every day, so astronauts may experience multiple sunrises and sunsets in a relatively short period of time. This frequent sunrise and sunset change may have an impact on the astronaut's biological clock and mental state.

On the one hand, frequent sunrise and sunset changes can disrupt an astronaut's biological clock. The body's biological clock is an internal biorhythm system that controls our sleep-wake cycle and other physiological processes. When we are exposed to irregular sun patterns, the biological clock can be disrupted, leading to problems such as sleep disturbances, fatigue, and mood swings. During space flight, astronauts' biological clocks can be disturbed due to frequent sunrise and sunset changes, resulting in a decrease in the quality of their sleep.

On the other hand, frequent sunrise and sunset changes may also have an impact on the astronaut's mental state. Sunrise and sunset are one of the most beautiful moments of the day on Earth, and they represent new beginnings and ends. However, in space, astronauts may feel the passage of time blurry and lose their perception of time due to frequent sunrise and sunset changes. This can lead to mood swings and increased psychological stress in them, as they are unable to feel the changes in sunrise and sunset as they do on Earth.

So, what are the specific effects of multiple sunrises and sunsets per day during space flight on astronauts' psychology and sleep?

First, frequent sunrise and sunset changes can lead to a decrease in the quality of sleep for astronauts. Normally, our bodies and brains regulate our sleep-wake cycle by sensing daylight. However, in space, astronauts can be disrupted with their biological clocks and sleep-wake cycles due to frequent sunrise and sunset changes. This can lead to a decrease in the quality of their sleep, with insomnia, dreaminess, and poor sleep.

Second, frequent sunrise and sunset changes can have an impact on the astronaut's mental state. Sunrise and sunset are one of the most beautiful moments of the day on Earth, and they represent new beginnings and ends. However, in space, astronauts may lose their perception of time and not be able to perceive the changes in sunrise and sunset as they do on Earth. This can lead to mood swings and increased psychological stress in them, as they are unable to experience the beauty of sunrises and sunsets as regularly as they do on Earth.

Frequent changes in sunrise and sunset can lead to the following psychological effects:

1. Distorted sense of time: Frequent sunrises and sunsets can disrupt astronauts' perception of time, making it difficult for them to distinguish between day and night, resulting in a chaotic sense of time. Time distortion refers to the phenomenon of changes in people's perception of time in a particular environment or situation. In space, the distortion of the sense of time can manifest itself in the following ways: Loss of time reference: the lack of a regular day-night cycle as a time reference causes the perception of time to become blurred. Rhythm disorder: The rhythm of work and life is different from that on Earth and may affect the judgment of the passage of time. Mission-intensive: A tight schedule of tasks can keep astronauts focused on their work and ignore the passage of time. Distorted sense of time can have the following effects: Difficulty in planning and decision-making: Difficulty in accurately estimating the time required for a task, affecting the making of plans and decisions. Fatigue management problems: The inability to accurately perceive the level of fatigue can lead to overexertion. Increased psychological stress: Feelings of uncertainty about time can increase psychological stress. To combat the distortion of the sense of time, the following measures can be taken: Use timekeeping tools, such as clocks, timers, etc., to help establish the concept of time. Make a detailed plan: Define tasks and breaks to improve time control. Communicate regularly: Communicate with teammates about time and remind each other. Conduct time training: Improve sensitivity and judgment of time.

   Time distortion is not only seen in the space environment, but can also occur in other situations, such as high-intensity work, prolonged solitude, etc. Understanding and responding to time-sense distortions is important for maintaining physical and mental health and productivity.

2. Mood swings: This unconventional environment can cause mood swings, such as anxiety, depression, or excitement.
3. Increased loneliness: The isolation of space may exacerbate loneliness, and multiple sunrises and sunsets may further emphasize isolation from Earth.
4. Psychological stress: The complexity and uncertainty of the task can increase psychological stress.

5. Decreased productivity: Distorted sense of time and changes in mood may affect astronauts' productivity and concentration.

   Effects on sleep include:

6. Sleep cycle disorders: The biological clock is disrupted, making it difficult to establish regular sleep patterns. Sleep cycle disturbance refers to the disturbance or disruption of an individual's sleep-wake cycle, resulting in abnormal changes in sleep quality and sleep duration. This disorder can be caused by a variety of factors, including lifestyle, environmental conditions, job requirements, psychological factors, etc. Common sleep cycle disorders include the following: Insomnia: Difficulty falling asleep, poor sleep quality, or waking up early, causing you to feel tired and sleepy during the day. Insomnia syndrome: Persistent insomnia problems that may be related to chronic stress, anxiety, depression, and other factors. Sleep apnea syndrome: Repeated pauses in breathing during sleep, leading to decreased sleep quality and daytime sleepiness. Inverted jet lag: The sleep-wake cycle is out of sync with the rhythm of daily life due to changes in time zones or irregular schedules. Night-shift work syndrome: daytime sleepiness and nighttime insomnia may occur due to disruption to sleep duration and quality due to long-term night shifts. Circadian rhythm disorder: Disturbance of the sleep-wake cycle due to irregular life routines and prolonged exposure to insufficient or excessive light. Sleep cycle disruptions have adverse effects on an individual's physical and mental health. Long-term sleep problems can lead to problems such as poor concentration, memory loss, mood swings, and weakened immunity. Therefore, for individuals with sleep cycle disorders, it is advisable to try to maintain a regular sleep schedule, create a good sleep environment, avoid excessive stress and anxiety, and seek help from a medical professional if necessary.

1. Decreased sleep quality: Frequent light changes may affect melatonin secretion, leading to reduced sleep quality.
2. Increased fatigue: Lack of sleep can increase feelings of fatigue and affect physical and mental recovery.
3. Compromised immune system: Long-term sleep problems can weaken the immune system and increase the risk of disease.
4. Cognitive decline: Sleep deprivation can affect cognitive functions, such as decision-making and memory.

To cope with these effects, the following measures may help astronauts:

1. Establish a regular schedule: Try to schedule your schedule according to the time on Earth.
2. Use shading equipment: Create a stable light environment inside the spacecraft.
3. Psychological adjustment: Includes psychological training and support to cope with loneliness and stress.
4. Stay socially connected: Stay connected with family, friends, and colleagues on Earth.
5. Get the right amount of exercise: Promotes physical and mental health.

6. Provide a good sleeping environment: include a comfortable bed and a quiet space.

   In conclusion, frequent sunrises and sunsets during space flight have a significant impact on astronauts' psychology and sleep. However, with appropriate measures and support, astronauts can be better equipped to cope with these challenges, ensuring their physical and mental health and productivity in space.

Maintain a regular sleep schedule: Try to go to bed at the specified time, and maintaining a regular sleep schedule can help adjust your biological clock and improve sleep quality. Create a sleep-friendly environment: Inside the capsule, astronauts can create a sleep-friendly environment by adjusting factors such as light, temperature, and noise. For example, using blackout curtains, adjusting the temperature in the cabin, and using earplugs, etc. Perform bedtime relaxation activities: Doing some relaxation activities, such as deep breathing, meditation or reading, before going to bed can help astronauts relax and fall asleep. Maintain good mental health: Astronauts can maintain good mental health by staying in touch with family and friends, attending counseling and support groups, and more. This helps to reduce psychological stress and mood swings. Acclimatization: Before going on a space flight, astronauts typically undergo acclimatization training, which involves simulating the conditions of life and work in a space environment. This helps them better adapt to the various challenges of spaceflight, including frequent sunrise and sunset changes.

Sunrises and sunsets multiple times a day during space flight can have an impact on the astronaut's psyche and sleep. Frequent sunrise and sunset changes can disrupt astronauts' biological clocks, leading to decreased sleep quality and increased psychological stress. However, astronauts can cope with these challenges by maintaining regular sleep schedules, creating a sleep-friendly environment, engaging in bedtime relaxation activities, maintaining good mental health, and receiving acclimatization training.