One molecule – two actions for sleep

Every night, our brain does the magic trick of putting us to sleep and then bringing us back to wakefulness. We do this automatically, but exactly how this process is triggered has been a mystery until now. Now researchers from the Technical University of Dresden have taken an important step towards solving it.

They’re focusing on a tiny worm called C. elegans. Yes, it doesn’t sound serious, but this microscopic organism is a laboratory star. It has just one sleep neuron, which makes it the perfect object to understand how the mechanism of falling asleep and waking up works.

The protagonist of the discovery is a molecule called FLP-11. Once a sleep neuron is activated, it releases this molecule as a message to other brain cells. What is particularly surprising is that FLP-11 works as a double agent: it helps you fall asleep and… wakes you back up. It all depends on which cell it hits.

‘If the molecule enters the cells of wakefulness – they ’switch off” and the body falls asleep. But if it returns to the same sleep cell – it also “switches off”, and the body wakes up,” explains PhD student Lorenzo Rossi, the author of the experiment.

Such a biological trick allows not only to fall asleep, but also not to ‘hang on’ in the state of sleep for too long. It is economical, precise and beautiful, like a perfectly fine-tuned mechanism.

Why is this important for us? Because, despite all the differences, many sleep processes in humans and simple creatures are organised in a similar way. Scientists think it’s possible we have a similar ‘sleep switch’ too – and its discovery could help combat insomnia, narcolepsy and other sleep disorders.

‘We are just beginning to understand how the brain controls sleep,’ says Professor Henrik Bringmann, the project leader. – But now we know: sometimes even a single molecule can decide when we sleep and when we get up.”