Why has it taken so long to accept chronic fatigue syndrome is an illness?

It's hard to understand why that is when you see so many people suffering with this, it's a stigmatising illness. I think a lot of people don't understand it because they don't necessarily see when the person's unwell. So, if you remember I said, it's a very fluctuating illness. So people often see their colleagues or their friends on good days, and don't see them on bad days, and that makes it much harder to accept. But also, we don't have a clear understanding of what causes it and we don't have a medicine to give it, and that sort of vagueness makes it much harder for people to really believe in it.