In today’s 24/7 society, our activities are not dictated by the Earth’s daily light and dark cycle. But our bodies are still there, he transmits Newsweek.
Artificial light, night shifts and social jet lag can confuse our internal body clocks, affecting our mood, sleep, alertness and appetite. In 2011, a survey conducted by the National Sleep Foundation found that 9 out of 10 Americans said they used an electronic device before bed, 72% of teenagers and 67% of young adults used smartphones before bed.
Since this study was conducted, the percentage of Americans who own smartphones has more than doubled, and many of us now go to bed with our phones next to us.
However, research has shown that this screen time can throw off our body’s internal clock, which in turn could cause us to gain weight.
“Our sleep-wake cycles, alertness, mood, activity level, body temperature and appetite fluctuate throughout each day under the control of the so-called ‘master clock in the brain,'” Becky Conway-Campbell told Newsweek , researcher at the Bristol Medical School of the University of Bristol in Great Britain.
“Other clocks throughout the body are called peripheral oscillators, synchronized by neural and hormonal signals. One of the most powerful hormonal synchronizing signals is through large waves of cortisol (often known as the ‘stress hormone’) released by the adrenal glands each day in the early hours of the morning.”
This daily burst of cortisol can be altered by exposure to artificial light or by changes in daily light exposure – which happens when we travel in different time zones – leading to what is called circadian misalignment.
“Circadian misalignment is caused by our internal body clocks being out of sync with external cues of light and dark,” Conway-Campbell said. “As a population, we are now affected by circadian disruption, global light pollution that can be detected by satellites, and the use of devices that emit blue light late at night.
This circadian misalignment also disrupts the hormonal cycles that govern our body, leading to a series of negative side effects. “This can include symptoms such as brain fog, lethargy, chills during the day, overheating in the middle of the night, lack of appetite at the beginning of the day and binge eating later,” said Conway-Campbell.
To investigate the effects of hormonal disruption on eating behaviors, Conway-Campbell and her team administered cortisol-like hormones to a group of rats either in sync with or outside of their daily light-dark cycle. And the results were surprising.
Rats whose hormone injections were synchronized with their light-dark cycle ate 88.4 percent of their daily food intake during the active phase and only 11.6 percent during the inactive phase.
As well as misaligned circadian cycles, our cortisol levels can also be affected by stress, which has also been associated with weight gain and unusual eating patterns.
More work needs to be done to understand the impact of these hormonal disturbances on humans and what can be done to mitigate their negative effects.
“These types of studies will ultimately provide information that will be used for intervention strategies for the treatment of obesity-related metabolic disorders that target the cause rather than the effect,” said Conway-Clark.
Meanwhile, the group of jet-lagged rats, whose hormones were injected out of sync, ate 53.8 percent of their daily calories during the inactive phase, with no increase in activity during this period.
Although this study – which was published on September 29 in the journal Nature Communications Biology – was carried out on rodents, these results suggest that the disruption of our circadian cycle could determine our desire to eat late at night, which, according to previous studies, is associated with metabolic disturbances and weight gain, even when total calorie intake remains the same.
2023-10-12 19:07:06
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