The astronauts on the International Space Station see 16 sunrises and 16 sunsets every day, and the question of when to sleep, when to pray, and when to celebrate birthdays has caused genuine philosop

Key Points:

• The International Space Station (ISS) orbits Earth every 92 minutes, causing astronauts to experience 16 sunrises and sunsets daily, which disrupts their natural circadian rhythms evolved for a 24-hour cycle.
• To maintain crew health and cognitive function, the ISS operates on Coordinated Universal Time (UTC) with a structured daily schedule, and uses advanced LED lighting systems that simulate natural daylight cycles to regulate astronauts' biological clocks.
• Sleeping arrangements involve small, private sleep stations with tethered sleeping bags and ventilation to prevent suffocation in microgravity, yet astronauts still experience sleep deficits that impact performance and require strict protocols including light discipline and caffeine management.
• Religious practices and cultural observances are adapted to space conditions by following the launch-site timezone for prayer times and holidays, demonstrating the importance of maintaining familiar temporal and social rituals for crew morale and psychological well-being.
• Long-term space habitation reveals that humans cannot live solely by orbital time; sustaining life in space depends on preserving Earth-based temporal structures like days, weeks, and celebrations, which provide essential psychological anchors despite the radically different environment.