A short and non-comprehensive guide to Nightmare Races:

• They are held at 7.30pm during the winter months.
• They are generally trail, beach or hill races.
• They can be between 2 miles and 10 miles.
• They need to be tackled using torchlight.
• They are open to anyone.
• They ask for £1 donation for charity.
• They are surprisingly highly regarded by their participants.
• They usually don't have marshalls or timekeepers.
• They do have race results and a newspaper report though.
• They aren't entirely scary and are perfectly safe*

*Depends on your mentality and outlook.