Sleep also plays a role in regulating emotions and can affect mood: the emotional centers in the brain are less connected when a person hasn’t had enough rest so it’s harder to control one’s feelings. As a result, sleep-deprived people can be overly grumpy or giddy, says Von Dongen.

And this would be an additional challenge to Nutbeam’s decision making when, at a later point in the flight, Roberts suffered a stroke. Nutbeam had to give him more blood as well as fluid and medication to stabilise him. “I remember feeling quite emotionally overwhelmed,” says Nutbeam. “He must have been feeling terrible but was incredibly stoical.”

Understanding the effects of sleep loss can help people cope, says Smith. “People can prepare for it and think about how it might shape their decision-making,” he says. Nutbeam says that he knows that he is much less tolerant when he’s tired, which might have helped.

Teamwork

Nutbeam was also fortunate to have a dedicated team that helped to keep his sleep-deprived mind in check. In addition to the team aboard the plane, there was a remote support network keeping a close eye on their journey from afar.

During stopovers, when they were able to communicate, colleagues abroad informed the team of weather conditions to help ease the logistical decision making.

Nutbeam also had regular debriefs with his boss in the UK about treatment and what to do in various circumstances.

When the plane landed in Rothera, for example, Roberts had another gastrointestinal bleed. There was a doctor there to help. But Nutbeam didn’t want to leave Roberts, even though he was exhausted.

A call from his boss in the UK put things in order. She told Nutbeam to let the local doctor take over so he could get some sleep: he was the only one that could look after Roberts during the remaining flight. “It was the best advice in the world,” says Nutbeam. “Otherwise I think I would have stayed with him and been even more tired and psychologically broken for the final leg of the journey.”

Tense situations can be easier to handle when there are others around. “Being in a dangerous environment surrounded by competent people who are supportive is a good way of mitigating stress,” says Smith.

It all depends on the team dynamics, though: if people aren’t able to work well together it can have a negative impact on the functioning of the group. Personality traits – in particular agreeableness - can often predict who will be a good team player. “People that have to work in small groups in risky settings tend to be good at getting on with people,” says Smith. “They are good at communicating effectively and maintaining group function.”

Aftermath

After the final flight from Rothera, the plane landed in Punta Arenas, Chile. Roberts was transferred to a hospital where he was successfully treated. But Nutbeam didn’t feel like the mission was over yet. “I really didn’t want to let Malcolm go,” he says. “I wanted to go with him to the hospital even though I could hardly string a sentence together.”

Expedition groups often have similar reaction when they return. After having lived through an intense experience together, there is a sense of empathy among those who were there, says Smith. It can also be hard to communicate what it was like to people who weren’t present so there is a tendency to be drawn to those who shared the experience.

Nutbeam was able to visit Roberts regularly at the hospital and there was a daily meeting about his recovery which gradually helped him readjust.