According to one study, the brain functions of late risers and "larks of the morning" during working hours are different.
Researchers examined the brains of night owls with an hour bedtime and a wake hour of 10:15, as well as early birds.
The tests – conducted between 08:00 and 20:00 – revealed that night owls had less connectivity in areas of the brain related to the maintenance of consciousness.
They also had less attention, slower reactions and increased drowsiness.
The researchers stated that "night birds" were disadvantaged by the "constraints" of the typical workday.
They called for more research to understand the health consequences of night owls performing a work or school schedule that they are not naturally suited to.
"Fighting the innate rhythms"
The scientists took 38 people who were either night owls or larks in the morning (people who went to bed just before 11:00 pm and woke up at 6:30 am) and studied their resting brain function with the help of Magnetic resonance imaging (MRI).
The volunteers then performed a series of tasks at different times, from 8:00 to 20:00, and were asked to indicate their level of sleepiness.
The larks of the morning had the least sleep and had the fastest reaction time at the beginning of the morning tests. They were also significantly better at this time than the night owls.
In contrast, night owls had the least sleep and had the fastest reaction time at 20:00, although they did not do much better than the larks at that time.
Cerebral connectivity in areas with better performance and lower sleepiness was significantly higher in larks at all times, suggesting that connectivity among late risers is altered throughout the workday, explained the researchers. researchers.
The lead researcher, Dr. Elise Facer-Childs, of the Center for Human Brain Health at the University of Birmingham, said the findings "might be partly motivated by the fact that night owls tend to to be compromised throughout their life ".
Dr. Facer-Childs said: "At school, night owls must get up early, then they go to work and get up early, so that they have to constantly fight against their preferences and their innate rhythms. "
She said that there was a "critical need" to better understand how adapting to school life and work schedules that are unsuitable for people can affect health and productivity.
About 40 to 50 percent of the population said they prefer to sleep later and get up after 8:20, researchers said.
Dr. Facer-Childs added, "A typical day can last from 9:00 am to 5:00 pm, but for a night owl this could result in decreased performance during the morning, lower brain connectivity in consciousness-related regions, and increased sleepiness during the day.
"If, as a society, we could be more flexible in managing our time, we could do a lot to maximize productivity and minimize health risks."
Dr. Facer-Childs pointed out that differences in cerebral connectivity are not a type of lesion and are probably reversible.
The study also has certain limitations.
The tests did not include brain function later in the day and it is possible that other factors, such as lifestyle choices, were not considered in the study. study, may have affected the results.
Dr. Alex Nesbitt, a consulting neurologist at King's College London, who did not participate in the research, said that the study had added that a person's brain performance was influenced not only by the time of day, but also by its biological clock.
"It is becoming increasingly clear that these factors are important when routines 9 to 5 widely impose on people," he added.
The study's authors called for more research to determine whether other areas of the brain could be affected by being a night owl or a lark early morning.
Their research is published in the journal Sleep.