Public conferences: our biological clock rules our health

What if our health depends on when we’re active… And when we’re asleep? Two public conferences held on May 25, 2025, at the CHUM gave around 70 people the chance to better understand the significant impact of biological rhythms on our well-being.

Presented at the Canadian Chronobiology Congress: From Cell to Medicine and Society, organized by CHUM Research Centre researchers Valérie Mongrain, head of the Neuroscience research theme and Canada Research Chair in Sleep Molecular Physiology, and Petronela Ancuta, member of the Immunopathology research theme.

Nearly 150 students, partners and national and international specialists in biological rhythms, health, psychiatry and neuroscience gathered together for this national event sponsored by the Canadian Society for Chronobiology and supported by the Canadian Institutes of Health Research, the Sleep Network, the Canadian Sleep Research Consortium and the Society for Research on Biological Rhythms.

Live better with atypical rhythms

How do we reconcile our health with off-kilter schedules? This question is at the heart of the conference, facilitated by Dr. Diane Boivin (McGill University) and Annie Vallières (Université Laval), and is posed to everyone from those working the night shift to chronic night owls.

Sleep is an active process, the facilitators note, and it is essential to both physical and mental recuperation. Most of us need to get 7 to 9 hours of sleep per day, but not necessarily all at once.

However, our biological clock—the master clock in our brain that sets the clocks in every other organ—is not equipped to deal with irregular schedules and can become dysregulated. Generally, this internal clock syncs based on natural light exposure, allowing us to stay on the right time.

“The rhythm of our biological clock is not very flexible, for example, even if you have a regular night schedule. According to the largest studies, 25% of people are able to truly adjust. Individual differences, such as age and sex, for example, also play a part,” says Dr. Boivin.

Outcome: fatigue, digestive issues, depression, cardiovascular disease and increase risk of accidents.

But all is not lost. Vallières shared some concrete advice on how to sleep better even with an atypical schedule:

• Prioritize sleep time, minimize noise and with support from loved ones
• Stay active after awakening
• Avoid coffee and stimulants for at least four to five hours before going to sleep
• Sleep during set hours in the dark (get up and go to bed at set times as much as possible)
• When experiencing insomnia, get out of bed, stay in the dark and go back to bed when you feel drowsy or after 15 minutes
• Avoid using screens in bed and for an hour before going to bed

Watch the conference

Daylight Saving Time: a simple adjustment or a danger for public health?

In his powerful lecture, Dutch researcher Roelof Hut (University of Groningen) argued for the abolition of Daylight Saving Time (DST).

The root of the issue is the growing disconnect between social time, the time our watches tell, and our biological time.

“Our bodies sync to sunlight, not wall clocks. So, the changing of time in the summer adds to this disconnect, especially for teenagers and late night chronotypes. Summertime is nothing but the use of an incorrect time zone,” he says.

The scientific literature is clear on the consequences of this chronic “social jet lag.” It leads to increased risk of depression, metabolic issues and worse academic outcomes.

Hut’s thesis is supported by international scientific data and longitudinal studies, according to which no longer switching to Daylight Saving Time makes it easier to follow natural rhythms and better our collective health. 

Like several learned societies and internationally renowned specialists, he campaigns for the return to permanent solar time, as our biology dictates.

Watch the conference

What if we reset our lives to the right time?

The research presented during these two public conferences reminds us of one very important thing: our body lives on its own rhythm and trying to force it to follow society’s has real consequences on our health.

If we can understand our biological clocks better, it gives us the power to act.

Individually, you can start tonight: reduce your exposure to blue light, sleep at regular times, and act like you truly value your rest.

Collectively, we can restructure our work hours, our public policies and especially the time change.

The science is clear: following our natural rhythms is an investment in a healthier society. We could be the ones to take this step, for ourselves and the generations to come.