New research suggests that thinking the glass is half empty could actually be good for you, and that being gloomy could be the key to beating stress.

They've concluded that it's feelings of uncertainty that lead to anxiety or stress, and expecting the worst can bring a sense of calm.

The research was carried out at University College London.

For example, the fear of going to the dentist is often worse than your check up, and most of the stress is around the fear of not knowing.

The study asked 45 students to play a computer game lifting up rocks, and they got a mild electric shock if there was a snake underneath it.