New insight pertaining to how we fall asleep and wake up might help develop new treatments for conditions like insomnia and seasonal affective disorder. The research is published in the journal Nature Communications.
The part of the brain regulating circadian rhythms by prompting us when to wake and when to sleep is the suprachiasmatic nucleus (SCN) in the hypothalamus. They contain ion channels known as BK channels that are thought to mediate the communication between neurones throughout the body.
The team of researchers behind the new study, led by Prof. Andrea Meredith, wanted to understand whether the BK channels located in the SCN influence circadian rhythms. They studied the SCN of mice to find out; it is to be noted that despite mice having a sleep pattern opposite to ours as they stay awake at night and only sleep during the day, the link between the activity of neurones and sleep-awake cycles in the two species is similar.
A group of the mice were genetically engineered to have their BK channels in the SCN activated the whole time. Activity in BK channels of these mice and normal ones was studied with electrodes in SCN neurones.
The findings show that mice unable to inactivate their channels (the genetically-modified ones) had lower neuronal activity, which caused them to remain awake for a longer time during the day.
The researchers explain that normal mice have inactive BK channels during the day when they sleep and active channels when they are awake at night. Inactive daytime BK channels are correlated with greater neuronal activity in the SCN which causes the mice to sleep while active ones at night are linked with decreased neuronal activity, thereby prompting wakefulness.
The authors write that their research is the first to demonstrate how deactivating BK channels is essential in regulating the circadian rhythm of the brain, and thus sleep-wake cycles.
“We knew that BK channels were widely important throughout the body. But now we have strong evidence that they are specifically and intrinsically involved in the wake-sleep cycle. That’s really exciting,” says Meredith.