An Indian-American scientist at Northwestern University in the US state of Illinois has found that a simple two-cycle mechanism controls waking-up and going-to-sleep process in animals during a 24-hour day.

Ravi Allada, circadian rhythms expert, recently discovered how an animal’s biological clock wakes it up in the morning and puts it to sleep at night. A simple two-cycle mechanism turns key brain neurons on or off during a 24-hour day.

The clock’s mechanism is much like a light switch, as per the findings published in the journal Cell on Thursday.

In a study of brain circadian neurons that govern the daily sleep-wake cycle’s timing, Mr Allada and his research team found that high sodium channel activity in these neurons during the day turn the cells on and ultimately awaken an animal, and high potassium channel activity at night turn them off, allowing the animal to sleep.

Investigating further, the researchers were surprised to discover the same sleep-wake switch in both flies and mice.

“This suggests the underlying mechanism controlling our sleep-wake cycle is ancient,” Mr Allada was quoted as saying Northwestern University as saying.

“This oscillation mechanism appears to be conserved across several hundred million years of evolution. And if it’s in the mouse, it is likely in humans, too,” Mr Allada, professor and chair of neurobiology in the Weinberg College of Arts and Sciences, said.

Better understanding of this mechanism could lead to new drug targets to address sleep-wake trouble related to jet lag, shift work and other clock-induced problems. Eventually, it might be possible to reset a person’s internal clock to suit his or her situation.

The researchers call this a ‘bicycle’ mechanism. Two pedals that go up and down across a 24-hour day, conveying important time information to the neurons.

That the researchers found the two pedals – a sodium current and potassium currents – active in both the simple fruit fly and the more complex mouse was unexpected.

“Our starting point for this research was mutant flies missing a sodium channel who walked in a halting manner and had poor circadian rhythms.

“It took a long time, but we were able to pull everything – genomics, genetics, behavior studies and electrical measurements of neuron activity – together in this paper, in a study of two species,” Mr Allada said.

“Now, of course, we have more questions about what’s regulating this sleep-wake pathway, so there is more work to be done,” he added.