Sleepwalking on a motorbike

Consciousness is really weird.

Shortly after moving to the UK from Canada, Jackie was lodging with an elderly woman. "One morning she asked, 'Where did you go last night?'" Jackie says. Jackie said she had not gone anywhere. "Well, you went out on your motorbike," the landlady replied. Jackie was shocked. She immediately asked if she had been wearing her helmet. "Oh yes, you clomped down the stairs and you had your helmet and you went out," the landlady said, adding that she had been gone for about 20 minutes.

Jackie had no recollection of her moonlit ride because she was asleep at the time. And there were no other clues to indicate she had been out, as she had returned the motorbike to exactly the same place it had been before.

What explains this incredibly complex behaviour, apparently arising in deep sleep?

We have known for years that certain animals like dolphins, seals and birds can sleep with one half of their brain at a time, allowing them to swim or fly while sleeping. In humans, this does not occur, but we do now know that sleep and wake can exist in different parts of the brain at the same time. When sleep-deprived, our brains show small areas of the cerebral cortex, the outer surface of the brain, exhibiting "local sleep" - electrical activity consistent with sleep.

Studies of sleepwalkers show that the parts of the brain controlling vision, movement and emotion appear to be awake, while areas of the brain involved in memory, decision-making and rational thinking appear to remain in deep sleep. These findings to some extent explain why sleepwalkers may appear to be awake - with eyes open, speaking and performing difficult tasks like riding a motorbike - but behave in an odd manner, and have no (or only limited) recollection.

For the most part, behaving like this is inconvenient or embarrassing. People may make phone calls or send texts in the middle of the night, find themselves wandering outside incompletely clothed, or cook meals in their sleep. "I know one person who every night would get up and sing the national anthem and then go back to bed," says Prof Meir Kryger, of Yale University.
http://www.bbc.com/news/magazine-42267790