Dr. Shimon Amir researches circadian rhythms and clock genes. (photo from Shimon Amir)
When our circadian rhythm is disrupted, it can cause a brain disorder that manifests in a series of detrimental conditions too numerous to list, but that includes insomnia, depression and Parkinson’s disease.
“Circadian rhythms are daily observations in behavioural, physiological and metabolic processes,” explained Dr. Shimon Amir, professor of psychology, Concordia University in Montreal, and director of the university’s Centre for Studies in Behavioural Neurobiology. “In fact, everything you can measure in an organism follows a daily rhythm – a 24-hour cycle generated by internal clocks present in each and every cell in our bodies. And they are synchronized with the environmental light cycle. So, there is tuning between the internal rhythms and the solar cycle. Those are the rhythms.
“Most people might think that rhythms are driven by the light-dark cycle, but that’s not the case. They are generated by a clock that is present in every cell. The clocks are made of a set of genes called ‘clock genes’ and they oscillate – form feedback logs that last each cycle, with each cycle lasting about 24 hours.”
Amir was born and raised in Israel and moved to Montreal for his PhD. He went back to Israel to work at the Weizmann Institute of Science, but later returned to Montreal to teach and do research on circadian rhythms and now, too, clock genes.
According to Amir, circadian rhythms allow organisms like flies, rats, monkeys, humans and even plants to anticipate and respond to the demands of their environment.
“Rhythms can be disrupted by various means,” he said. “Ones that are most common are traveling across time zones, working shift work and eating at the wrong times. But, the main reason for the disruption is movement across time zones. Your clock is synchronized to your location. So, if you move from, say, Vancouver to Montreal, the clock has to be advanced, as you’ll wake up in Montreal three hours earlier, right? That takes time and the mismatch between environment and internal cycles causes various metabolic, behavioural, cognitive and other problems.”
While there are clocks in every cell of the body, all these clocks report to the master clock in the brain. That clock receives input from the eyes – light information that resets the master clock daily.
When we use lights at night, the master clock gets disrupted. “The clock is very sensitive to light at night,” said Amir. “Say you’re asleep and you want to go to the bathroom in the middle of the night. You turn on the light and that causes a disruption of the clock. Another way to disrupt the clock is the time that you eat. Eating should occur during the day.
“The reason light is so disruptive at night is that one arm of the clock is a hormone called melatonin. Melatonin is exceedingly sensitive to light. It is secreted during the night and is suppressed during the day. But, if you turn on the light at night – even very brief exposure to light at night – it suppresses the melatonin rhythm.”
Amir suggested using a sleep mask to keep light away, as well as learning to use the washroom at night without turning on a light. “You can adapt to the dark very quickly and be able to see,” he said.
While Amir’s initial research interest was in circadian rhythm, over the last 10 years, he has expanded his focus to other clocks in the brain – those that control different types of behaviours and pathological conditions, such as depression, anxiety, drug addiction and diseases like Parkinson’s.
Through experiments with mice and rats, Amir has been working to configure which brain clock controls, or affects, how the rodents handle stimulation and what happens if these clocks are turned off or disrupted.
“So, the clocks are made of several particular genes called clock genes,” said Amir. “We have various molecular, genetic and viral tools to manipulate those genes directly … in different regions of the brain…. We’re seeing what happens when an animal that has a brain region that doesn’t have a clock or particular clock gene that stops the clock … how the animal behaves and what are some of the pathological consequences of this condition.”
Amir and team use various animal models of disease, looking into what happens when you take out the clock and if it correlates with enhanced depression and anxiety.
“The circadian rhythm is really a very fundamental system that you can say controls everything,” said Amir. “When the system is disrupted, it has important implications for varied disorders.”
The main goal is to understand the evolutionary function of the clocks and what they do to enable adaptation of organisms to their surroundings. But, also, the hope is that, by having better understanding, it will help in identifying new avenues of therapies.
With jet lag being such a hot topic in regards to circadian rhythm, Amir suggested a few ways to keep it at bay. “There are some ways to shorten jet lag, but there’s no way to avoid it,” he said.
“When you go east, you have to be exposed to light in the morning, in order to readjust to the new time zone. When you are exposed to light early in the morning, it induces in the clock a ‘face advance,’ it advances the clock. But, if you go west, you have to be exposed to light at night, early night. The transition between the evening and night, that’s where you have to be exposed to light, and that’s where it is ‘face delay.’ It will delay the face of the clock, because you have to wake up later when you go west.
“You need to be intentionally exposed to light in the evening or have light exposure a bit longer before you go west … or wake up very early, be exposed to light early in the morning, if you go east.
“Going through jet lag is very unhealthy,” he said. “If you do it very often, it will affect you in various ways, negatively, of course. Except, you can’t avoid it … as you go see family and grandchildren, and others, in Israel.”
Rebeca Kuropatwa is a Winnipeg freelance writer.