Julie Fallon, of Ardgowan School, asks :-

When travelling in a space rocket do you go to sleep or not?

Colin Keay, a space physicist at Newcastle University in Australia, responded.

It would be rather hard to go to sleep in a rocket if its motors were firing. The noise, vibration and the force producing the acceleration would wake you up even if you had been asleep. If we are talking about a rocket in orbit, or a space station, the situation is very different because of the weightless conditions which can lull one to sleep very easily.

But being weightless, while pleasant, can after a time become very harmful to a human being. Russian cosmonauts who have spent longer times in space than anyone else have been almost unable to walk after returning to Earth. Their bone structure and muscles are just too weak to support them, much less provide walking power.

Conditions for astronauts in space need to be as close as possible to those on Earth. They should maintain their circadian rhythm, that is to say they should sleep as normally as possible on a 24-hour cycle. This is a problem on a typical Space Station like the Russian Mir or American Skylab where they experience a continual cycle of 50 minutes of daylight followed by 45 minutes of darkness.

To overcome this problem the crew members take it in turns to shut themselves away for seven or eight hours in a dark compartment, sleeping in a sleeping bag fastened against the wall so they don't float about in their dreams.