It was this big – in my dream Dmitriy Maruk/EyeEm/Getty

A man has dreamed in colour for the first time after undergoing radiotherapy to treat a tumour on his eye.

The 59-year-old Australian previously dreamed exclusively in black and white. But when he received radiation therapy to the front and side of his head for four weeks, he began dreaming in vivid colour.

Some of these dreams involved mentally flicking through coloured images of former girlfriends, cars, and fish he had caught. In one, he saw colourful algebraic symbols emerge from a blackboard and whizz towards him.


Why he had previously dreamed only in black and white is unclear, but it may be because of the type of television he grew up with. People who saw only black-and-white film and television as children seem more likely to dream in greyscale throughout their lives. Australia didn’t fully convert to colour television until 1975.

Altered brain activity?

His switch to colour dreaming may have been sparked by the radiation’s effect on electrical brain activity, says radiation oncologist Michael McKay, who treated the man at the North Coast Cancer Institute in New South Wales.

There is some evidence that radiation can affect electrical brain activity. People exposed to radiation during the Chernobyl disaster, for instance, showed unusual electrical brain activity on electroencephalography (EEG) tests. Over a third also reported abnormal dreams.

Abnormal dreams have not previously been associated with radiotherapy treatment of the head, but this may be due to lack of reporting, says McKay. In this case, the man had an easily-curable eye tumour, whereas many others who receive radiation to the head have terminal brain tumours. This could make them less likely to notice or remark on strange dreams.

Read more: Heal yourself from inside your dreams

The Australian man did not have EEG tests, so the effect of radiotherapy on his brain remains a mystery. “But if the radiation was affecting [EEG-detected] activity, then that could quite readily change the dream experience,” says Simon Cropper at the University of Melbourne.

Back to black

The man’s dreams may have become more colourful in response to altered brain activity because colour is an easily-modifiable component of perception, says Cropper. For example, hallucinogens – which also modify the patterns seen on an EEG – almost always heighten the experience of colour.

But there could be a more banal explanation, says Robert Stickgold at Harvard University. The radiation may simply have caused the man to wake up more frequently in different stages of sleep, increasing the chance of noticing and remembering coloured dreams, he says.

The man’s tumour was cured by radiotherapy and he reverted to black-and-white dreaming a few days after finishing treatment. McKay hopes other people will come forward if they have had similar dream-altering experiences during radiotherapy, so the phenomenon can be studied further.

Journal reference: Sleep Medicine, DOI: 10.1016/j.sleep.2017.01.010