TV sent you to sleep? It’ll ruin your rest

IT’S easy to nod off in front of the television, but this may be a bad idea if you want to be alert the next day.

Hearing strangers’ voices, like those of actors in a late-night film, interrupts your sleep, evidence has shown. But the voices of family members late at night are far easier for the sleeping brain to ignore.

Researchers recruited 17 people to sleep in a laboratory, while playing them the voice of either a stranger or someone close to them, such as a family member. For 90 minutes at a time, throughout the night, they heard the voices at the volume of a whisper. Participants had many more ‘micro-arousals’ – interruptions to sleep – when they heard the stranger’s voice.

This is likely to be a hangover from our hunter-gatherer past, when it was important to sleep with one ear open, and unknown voices could mean an imminent attack. The stranger’s voice was also linked to more, and stronger, K-complexes – a type of brainwave believed to show people are processing sounds as they sleep.

The stranger’s voice appears to trigger a greater level of processing, which kicks in more rapidly, even among those in deep sleep.

Professor Manuel Schabus, senior author of the study from the University of Salzburg, said: ‘These results suggest that sleeping in front of the television, or with the radio playing, is not a great idea. With strange voices in the background, the brain is constantly having to analyse what is going on and whether it is dangerous or not dangerous. That could mean very fragmented and interrupted sleep.’

The findings, published in the journal JNeurosci, could explain why it is harder to sleep in a hotel, with strange voices in the corridor, than at home in your own bed.