SCIENTISTS’ WORK ABUZZ WITH INSIGHTS ON SLEEP

THE first seasonal cold front has swept across the country, and for many South Africans it was once again a struggle to wake up and get out of bed.

Why temperature and dark mornings have such an affect on our sleep behaviour, has puzzled scientists for many years. Now, the fruit fly might have the answer to how get a better night’s sleep. Neurobiologists from Northwestern University in the US believe they have discovered a clue as to what causes temperature to disrupt sleep, while looking at the brain of the fly.

They found a “thermometer” circuit, which, they believe, relays information about cold temperature from the fly’s antennae to its brain. They found that cold and dark conditions can inhibit neurons in the fly’s brain that promote activity and cause the insect to wake up. “This helps explains why, for both flies and humans, it is so hard to wake up in the morning in winter,” said Marco Gallio, associate professor of neurobiology at the university’s Weinberg College of Arts and Sciences. “By studying behaviours in a fruit fly, we can better understand how and why temperature is so critical to regulating sleep.”

Gallio and his colleagues’ research was published inthe journal Current Biology. They described in the paper how, what they call “absolute cold” receptors in the fly’s antennae, respond to temperatures below 25 °C.

The researchers then traced how these receptors target a small group of neurons in the insect’s brain that form part of a network that controls its sleep. When the cold receptors are active, the target cells that are normally activated by morning light are shut down.

“The principles we are finding in the fly brain, the logic and organisation, may be the same all the way to humans. Whether fly or human, the sensory systems have to solve the same problems, so they often do it in the same ways,” says Gallio.

Ultimately, all of this might help in getting a good night’s sleep, and waking up refreshed even on a cold and dark morning. “The ramifications of impaired sleep are numerous – yet we still do not fully understand how sleep is produced and regulated within the brain and how changes in external conditions may impact sleep drive and quality,” said Michael Alpert, co-author of the paper. | Shaun Smillie