by Jo Marchant
What is rarely mentioned today about the famous Aschoff and Wever bunker, built a few years later, is that it did not contain just one underground apartment, but two. The parallel units were almost identical, with matching beds, kitchens, and record players. But there was a very important difference: one of them was completely enclosed in a heavy capsule of cork, coiled wire, glass wool and steel, through which no electromagnetic radiation could pass; anyone living inside was completely cut off from Earth’s magnetic field. The goal was to show that the armor made no difference to the volunteers’ biological clocks and to prove, once and for all, that Brown was wrong.
Between 1964 and 1970, more than 80 volunteers remained in the two units. As Aschoff predicted, their circadian rhythms continued. But there was a problem; the results in the two groups were not the same. In the unshielded bunker, isolated from clocks and the sun but still exposed to magnetic fields, people’s sleeping and waking patterns moved away from the solar day, reaching an average period of 24.8 hours.
But when the magnetic fields were also blocked, the volunteers’ circadian cycles deteriorated further. Their day length slipped even longer. There was much more variation between individuals. And their different rhythms were much more likely to decouple. As mentioned earlier, Aschoff championed desynchronization as one of his main findings. Yet in those six years it only happened in the armored bunker, cut off from the Earth’s magnetic field. Wever found that if he exposed the volunteers to a similar artificial field, all of these effects were reversed.