But it’s a mystery that’s slowly being solved. The latest and most intriguing clue comes from Enrica Audero from the European Molecular Biology Laboratory, working together with European researchers and a special strain of mice. Audero has shown that altering the balance of the signalling molecule serotonin in the brainstems of mice can lead to sudden demise, in a way that resembles the unexpected death of SIDS babies. The mice spontaneously go through “crises” where their basic body functions like temperature control and their heartbeat go haywire.

Audero’s work builds on research published by an American group two years ago, which first suggested that SIDS is the result of faults in the way our brains reacts to serotonin.