英国每日邮报的一篇报道说,在太空中,没人能听到宇航员打呼噜,但是,这或许正是他们失眠的原因.

Daily mail: In space, no one can hear you snore - but that's probably because you're not asleep.

A study has revealed most astronauts suffer serious levels of sleep deprivation that could be putting their lives in danger.

The reasons for this are poorly understood, but the sun rising and setting every 90 minutes when orbiting

Earth on the International Space Station (ISS) is thought to be one possible cause.

Scientists studied the sleep patterns of 64 astronauts on 80 space shuttle missions and 21 International Space Station (ISS) crew members before, during and after spaceflight.

They found that on average astronauts get less than six hours sleep a night on orbiting space shuttles and just over six hours on ISS missions. This was despite the American space agency Nasa scheduling 8.5 hours of sleep per night for space-travelling astronauts.

Around three-quarters of astronauts also resorted to sleeping pills during spaceflight, raising concerns about the effect the drugs may be having on their performance.