The basis of this new view is blindingly obvious once it is pointed out: everyone feels miserable when they are ill. That feeling of being too tired, bored and fed up to move off the sofa and get on with life is known among psychologists as sickness behaviour. It happens for a good reason, helping us avoid doing more damage or spreading an infection any further.
It also looks a lot like depression. So if people with depression show classic sickness behaviour and sick people feel a lot like people with depression – might there be a common cause that accounts for both?
The answer to that seems to be yes, and the best candidate so far is inflammation – a part of the immune system that acts as a burglar alarm to close wounds and call other parts of the immune system into action.
