Did you know that the time of day you take medication, get a vaccine, or receive health care could have a dramatic effect on how well it works?
It has everything to do with your internal biological clock, or your “circadian rhythms” as they are known in science.
Your circadian rhythms are what help your body adjust to the changes that occur on the Earth as it rotates once every 24 hours.
“We can think of circadian rhythms as representing an internal day within and what they do is fine-tune every aspect of our physiology and behavior to the demands of the resting activity, the light-dark cycle,” explained Russel Foster, professor of circadian neuroscience at the University of Oxford and director of the Sleep and Circadian Neuroscience Institute (SCNi).
So, for example, our blood pressure rises early in the morning in anticipation of more morning activity and can thus deliver more oxygen and nutrients to our tissues. Cortisol, one of the stress hormones, also rises in the morning in anticipation of more activity.
At the end of the day, your body shifts into a different metabolic state. During the night, we start using stored calories instead of burning the calories we took in during the day. At night, there is also a release of growth hormones which regulate tissue growth and repair.
These are just a few examples. Your body is constantly adjusting to your sleep-wake cycle whether you know it or not.
When the sleep-wake cycle is misaligned
We have this internal biological clock that ticks but needs daily adjustments to keep it aligned with the outside world.
“The most important factor is the light, particularly at dawn and dusk,” Foster said. “Thus, exposure to light sets the internal clock to the external world.”
One of the most obvious examples of a mismatch between your internal clock and the outside world is jet lag. To overcome jet lag we need to expose ourselves to the local light-dark cycle. But what about people who always work at night?
“Individuals are trying to work while their whole physiology and biology says they should be asleep,” Foster said.
The assumption has often been that night shift workers eventually adapt to the demands of night work. But, according to Foster, a whopping 97% don’t.
“You’re constantly running the biology outside of its normal range by activating the stress axis,” she said.
“The long-term consequences can be very serious. We now know that there are higher rates of cardiovascular problems, heart attacks, strokes, higher rates of metabolic abnormalities such as type 2 diabetes and obesity, and even higher rates of cancer long-term”. fixed-term night shift workers”.
These are the long-term effects, but working nights and, more generally, lack of sleep also have short-term effects. These can include increased irritability and impulsiveness, a lack of empathy and a sense of humor. Our memory has also declined, Foster says.
“It’s not just our memory. It’s our ability to find new solutions to complex problems,” he explained. “So, not getting enough sleep and working nights is more than just feeling tired at an inappropriate time. It’s a major impact across the health spectrum.”
So what can be done to combat these risks, in industries where night work is essential?
Foster believes we need to use all of this research to help improve conditions and reduce the risk for those workers.
“We now know that disruption of sleep immediately before or after a vaccination will reduce the effect of that vaccination,” Foster said. “So for our frontline staff, we need to make sure they are fully rested before and immediately after vaccination to give them optimal protection.”
He says employers of night workers must also alert their employees to the dangers associated with night work and be vigilant about health issues, with more regular health checkups to ensure conditions don’t become chronic.
Chronopharmacology: adapting health care to our biological clocks
Foster also says your biology is so dynamic throughout the 24-hour day that the effectiveness of medications will change throughout the day.
“Morning vaccination has been shown to be more effective in generating an antibody response than afternoon vaccination,” he said, describing a study of influenza vaccines.
“Another really key area has been the timed delivery of chemotherapy. And the results are quite remarkable in one study. The same drugs, the same concentration, but given at two different times.
“At one time, five year survival was 45% of the group. On the same drug, different times that fell to 10% of the group. A huge difference between 45 and 10% survival and that was just changing the time”.
Of course, these findings only apply to a specific treatment, vaccine, or drug and may not apply generally, however, scientists are starting to see that the time of day matters in many different types of drugs and treatments.
Hypertensives and blood pressure medications are other examples, according to Professor Foster.
“One study showed that taking them before bed rather than first thing in the morning can cut your chances of having a stroke in half over a ten-year period,” he reveals.
Unfortunately, all this research has not yet translated into concrete actions in the health sector.
“Unfortunately, this medication timing information is not often integrated into medication administration,” Foster admitted.
“There is interest in this area, but the ability to use this information is a bit overwhelming with the enormous demands the medical profession faces at the moment to provide any type of treatment. I think it will come, but it is coming slowly.” .
How much sleep do I need?
“Sleep is a bit like a shoe size. One size absolutely does not fit all,” says Foster, who is also the author of Lifetime, a recently published book on the topic of sleep and circadian rhythms.
“One of the reasons I wrote Lifetime is because I was getting a little annoyed with the sleep sergeant majors saying, you gotta do this and you gotta do that…Sleep and circadian rhythms differ so much between individuals.
“We’ve now identified key genes that are associated with morning and evening. Small changes in those genes can actually make you go to bed later or want to go to bed early. It’s pretty remarkable.”
The first thing we need to do, says Foster, is figure out what kind of body clock we are and how much sleep we need.
“Are you able to function optimally and at a level you find satisfactory throughout the day to accomplish the tasks you need to accomplish?” he asks. “Then you’re probably getting enough sleep at night.”
“But if you need an alarm to wake you up, if you feel tired and cranky throughout the day, if you’re addicted to caffeine and sugary drinks…overly cranky, obnoxious, overly impulsive and really doesn’t act like before These are all very strong indications that you are not getting the sleep you need.
“So many people think sleep is just what you get,” Foster added.
“No, it’s not. It’s immensely dynamic, not just between individuals but as we age. What we need to do, each of us is define our individual sleep needs and then change our behaviors to optimize that sleep “.