Halloween is a strange time, a blend of Christian and pagan festivals when dark nights and superstition have produced some unusual traditions.

You will see pumpkins on doorsteps, children in costume and horror on the television. For those of us who happen to have been born on Friday the 13th, I am sure it will be a surprise to learn there is not just a film but a whole phobia named after the intense fear of the date*. I just thought I was special.

Have you noticed if your hospital has a ward 13? If you are in a big hospital, does it have a 13th floor? Is there a theatre 13, a clinic 13 or a room 13? This irrational fear of the number 13** is unusually common in the UK.

Irrational beliefs have crept into medicinal culture too. There is the famous “Q” word. One should never ever say it's “quiet”, because all hell will break out. Some surgeons have “lucky” shoes. Many emergency departments will be convinced it will be busy because of a full moon. Some seem to believe it is always the nicest people, or the recently retired who get the nastiest illnesses. Some believe everything comes in threes, that redheads bleed more and I am sure many of you will take 2 cannulas to the bedside, because if you didn't you would be bound to fail your first attempt.

Do you tell patients to bring an overnight bag so they won't need to stay in?

If a patient dies, why is the window often opened? Why does sitting down, especially on the toilet, seem to cause the phone to ring? And why do some people seem to be, or believe themselves to be, magnets for disaster?

These irrational beliefs or superstitions seem harmless enough, but is there a more sinister side to superstition that we should take heed of? Perhaps some people get anxious at work because of these beliefs. Any perceived changes could be due to this anxiety. Much effort, time and money has been spent on trying to prove or disprove these myths over the years (redheads don't bleed more by the way).

There is no such thing as luck. There are no unlucky patients or doctors. It isn't luck if someone gets better. It isn't bad luck that causes complications. We can't influence the laws of chance. Good luck charms do not work. We have created the belief in luck through a combination of confirmation bias with optimism or pessimism.

Medicine should not be associated with luck, we should have no part in any nonsense whatsoever. Beliefs should never influence decisions over evidence. We can remain optimistic for our patients. We can still hope. Those feelings and wishes can't be denied.

We just must be precise and careful with our explanations, how we describe chance and how we justify risk and harm. So, while others enjoy a night of make believe, lost in superstition, we must stay rational every day of the year. Walk under a few ladders, step on those cracks, spill some salt, open an umbrella indoors, choose the number 13 the next time you can, and maybe just take one cannula to the bedside next time. Be logical.

Medicine is a science of uncertainty and an art of probability. - William Osler

* paraskevidekatriaphobia

** triskaidekaphobia