For nearly 20 years, the European Space Agency (ESA) has been running variations of the same tedious experiment.
They recruit 20 young people to lie in bed for 60 days. Each participant is reportedly paid US$19,000 (AUD$27,814).
What’s the point of it?
Lying in bed is a relatively cheap simulation of spending time in space, where the body, even when moving about, does little to no work in the absence of weight and gravity.
Dr Angelique Van Ombergen, Discipline Lead for Life Sciences at the ESA, described bedrest as “the golden standard” for spaceflight analogues.
So, if you have 60 days to spare, and a lazy disposition, you can think of yourself as an astronaut of sorts.
In one shorter version, looking at sleep, the participants wore a comfy version of the astronaut suit and helmet – but in most of the studies, pyjamas or lounge wear are de rigueur.
Of course there is no beautiful view, or the fun of performing somersaults in zero gravity.
Gosh, what’s the catch?
The real work involves … staying in bed, on your back, with your feet raised above your head so fluids gather in your chest area. The bed is actually tilted to facilitate this.
And you never leave the bed.
Eating, showering and going to the toilet happens on the bed.
But at least you’re an astronaut, which is glamourous.
Taken for a spin
In a 2019 running of the experiment at a facility in Cologne, some participants, men and women, were granted a little variety to their day – when their beds were wheeled into a giant centrifuge.
Still lying on their backs, the participants, male and female, were spun at great speed, like numbers of a chocolate wheel. The centrifuge simulated a low-gravity environment, presumably similar to that created by the famous “vomit comet”.
The latest experiment, involving 20 young healthy men, was staged by scientists from the University of Bath – with a focus on the metabolic effects of living in space.
Soaring diabetes risk
In short, the new study investigated the impact of inactivity on blood sugar levels. The researchers expected it to be bad.
As researchers noted in a previous study:
“Many astronauts come back to Earth from space showing signs of pre-diabetes because weightlessness can lead to insulin resistance whereby the muscles and liver can’t absorb glucose to help regulate blood sugar levels.”
And of course astronauts are at least moving and bending and changing position, albeit in a weightless environment.
The new study looked at how bad it might get in people who aren’t moving at all – which might be the case for astronauts who would spend months getting to Mars, and years travelling further out in the solar system.
It has serious implications for the viability of long-haul space travel by humans.
The participants were fed “a much-reduced diet to compensate for their much-reduced physical activity and to stop them gaining weight”.
The idea was to match energy intake with output. Essentially, participants got the minimum number of calories to run their internal functions.
Presumably, this might also be a requirement for long-haul travel, where travellers uninvolved with running the spacecraft are rendered inactive as a means of reducing their consumption of resources. You see this sort of thing in the movies where astronauts are put to sleep.
The results
The study found that “long-term inactivity significantly increases blood sugar levels even if you reduce your food intake to avoid gaining weight”.
Specifically, average blood sugar levels among participants increased by around six per cent in the day. And by 10 per cent at night.
Their ability to dispose of blood sugar – to take up blood sugar into muscles – also decreased by 24 per cent. Nearly a quarter.
The ability to control one’s blood sugar is an important risk factor in developing cardiovascular disease or Type II diabetes.
The research team said that the reduction in calorie intake “did prevent participants from experiencing even higher blood sugar levels”.
The ESA is already making up the beds for new studies that will trial “counter-measures”. Meaning: strategies to reduce the risk of space travellers developing diabetes by the time they colonise distant shores.
