Our immune systems recall bacteria and viruses by collecting fragments of them to form 'memory T cells'.
These last months or years and help the body recognise a previous infection and react.
Researchers said the cells work in a similar way to the mind, extracting 'the gist' of the germs. We reduce the information to a vital core because the capacity of short-term memory in our brains and immune systems is limited so we focus on the essentials.
Support for the theory comes from studies that show long-term increases in the number of memory T cells following deep sleep the night after a vaccination.
An important factor is the hormone cortisol, which suppresses activity in the hippocampus - part of the brain involved in memory - and in the immune system during sleep.
Professor Born warned: 'If we didn't sleep, then the immune system might focus on the wrong parts of the pathogen.'
He hopes greater understanding of the immune system's 'memory' will aid vaccine development.
- Daily Mail