By Peter Wood
BBC News Online
Researchers think the human body clock could hinder space exploration.
Any manned venture to Mars would involve a lengthy stay
Russell Foster's team at Imperial College London, UK, is looking at how astronauts would cope away from Earth.
Foster says our "circadian rhythm is crucial. It stops everything happening at once and co-ordinates the right things to happen at the right time".
Whilst the human body is used to a 24-hour cycle, the day on Mars is an extra 39 minutes long, which could prove difficult for humans to adapt to.
The Imperial researchers are working in conjunction with the US National Space Biomedical Research Institute (NSBRI) and have been investigating the impact space travel has on human sleep behaviour.
As the NSBRI's website puts it, "the success of human spaceflight depends on astronauts remaining alert while operating highly complex, state-of-the-art equipment. A crucial factor of mission success is getting enough sleep".
Space is the most extreme shift-working environment. The crews on space missions sleep poorly, with astronauts averaging about two hours per night less sleep than they normally experience on Earth.
Previous research into nightshift workers has shown disrupted sleep patterns can lead to various health problems and diminished performance. For example, such workers are at a 50% higher risk of a car crash at three in the morning after four days of nightshifts.
Professor Foster commented at the recent BA annual Festival of Science in Exeter: "While many of the technical difficulties of space travel are well documented, there has been less research on the medical and health-related problems astronauts may encounter.
"The human body is used to a 24-hour cycle, which may prove difficult to regulate in space."
Research has shown the average human body clock has a period of 24 hours and 11 minutes, which is then corrected each day by the onset of dawn and dusk. The low levels of light in space are not able to reset the body clock properly which disrupts sleep patterns.
This combined with the deviation from the circadian rhythm can lead to under performance in demanding situations. As Professor Foster says, "you must not be half asleep or half awake; being so, might ultimately prove catastrophic".