Ever won the lottery? No? But did that stop you buying another lottery ticket? If the answer is another "no", you might call yourself an optimist.But according to researchers at University College London, human beings are naturally hopeful creatures.It is all in the brain, they say.A study suggests it is very efficient at processing good news:about 80% of people have a tendency to see the glass as half-full, not half-empty, even if they don't consider themselves to be optimists.The good news is that this brings a health benefit.Being upbeat and having a positive outlook on life reduces anxiety.A study of nearly 100,000 women showed a lower risk of death from heart disease amongst optimists.But it's not always good to be optimistic.The authors of the study point out the 2008 financial crisis may have been caused by analysts overestimating their assets' performance even in the face of clear evidence to the contrary.There are personal health risks too.Dr. Tali Sharot, lead researcher, said: "Smoking Kills' messages don't work because people think their chances of having cancer are low.There's a very fundamental bias in the brain.”But, as they say, every cloud has a silver lining.