UFO sightings have various possible explanations, ranging from natural phenomena to psychological effects. Many sightings result from misinterpreting bright lights, such as the planet Venus, or optical illusions caused by reflections or camera lens effects.
Psychological factors may also play a significant role. Some “abduction” stories are attributed to sleep paralysis, a sleep disorder that can cause hallucinations. Additionally, in the former Soviet Union and China some sightings resulted from secret military tests and from governments’ encouragement of the belief that the objects were of extraterrestrial origin to hide the true nature of the experiments.