Anew study in New York suggests that a preference for night-time over daytime activities may be associated with antisocial behaviour in adolescents, even in children as young as eight years old.
Those who prefer later bedtimes appear to exhibit more antisocial behaviour than those who like to wake early and participate in daytime recreational activities, reports Elizabeth J. Susman of Pennsylvania State University, US. “A preference for evening activities and staying up late is related to problem behaviour and is evident even in preteens,” she said.
Staying up late “contributes to lack of sleep and this, in turn, causes problems such as lack of control and attention regulation, which are associated with antisocial behaviour and substance use,” Susman added.
Susman and her team investigated the relationship between a preference for morning versus evening activities and antisocial behaviour in 111 subjects between eight- and 13 years old. They also correlated morning to afternoon levels of cortisol—the stress hormone associated with circadian rhythms—with behaviour and noted the age at which the subjects reached puberty.
The researchers found a number of factors were related to antisocial behaviour in the study group, particularly in the boys who tended to exhibit more rule-breaking behaviours than did their peers. The findings are published in the Developmental Psychology journal.
For girls, a preference for evening activities was associated with a higher incidence of relational aggression or aggressive behaviour towards their peers.
Boys who experienced prolonged high levels of cortisol—smaller decreases in cortisol levels from the time of awakening until 4pm—tended to have more behaviour problems than did their peers, the report indicates. The association was not true for girls, however. Normally, levels of cortisol peak in the morning upon awakening and plateau during the afternoon and evening.
Abnormalities in cortisol secretion have also been associated with clinical depression and antisocial behaviour in earlier studies, the researchers note. Boys who hit puberty at earlier ages tended to also engage in more rule-breaking and attention behaviour problems than did other boys, according to parent reports, and they self-reported more symptoms of conduct disorder.
Girls who were younger at puberty reported more relational aggression compared with their peers, study findings indicate.
Overall, the findings imply that “caregivers should be vigilant to bedtime activities of children and young adolescents,” according to Susman.
“Monitoring these activities is essential for making sure that children and adolescents are going to sleep in time to assure enough sleep for good functioning in school and otherwise,” she added.
Vitamins are vital
Meanwhile, another study suggests that teenagers who do not get enough of the nutrients commonly found in fruits and fish are more prone to underperforming lungs, asthma, coughing and wheezing. In a study conducted by Jane Burns and colleagues at the Harvard School of Public Health, the researchers found that teens with the lowest intake of fruit, and especially vitamin C, had weaker lungs compared to the others.
Teens who ate less vitamin E, found in vegetable oil and nuts, were more likely to have asthma. Based on these findings, Burns said that current recommended dose of vitamin C, 85mg a day, may not be enough for teens to have healthy lungs.
Many studies have connected unhealthy eating habits with lung problems. So, Burns and colleagues surveyed and tested 2,112 12th-graders from the US and Canada.
In keeping with previous surveys, they found that many teenagers ate less than the recommended amounts of fruit and vegetables; they reported this in their study, published in the journal Chest.
Only 11% took vitamin supplements on a daily basis.
Teens who consumed less fruit and lower levels of omega-3 fatty acids were more likely to have asthma and respiratory symptoms such as wheezing. Even moderate amounts of the omega-3 fatty acids were protective, Burns said, though fish, the best source of omega-3, was particularly unpopular with teenagers.
Omega-3s are also found in walnuts and flaxseed oil as well as some green vegetables.
Omega-3 fatty acids may work by counteracting inflammation in the lungs. The antioxidant properties in vitamins C and E as well as other compounds found in fruit probably protect cells lining the airways from free radical damage, Burns said.
A quarter of the adolescents they surveyed were smokers.
More than 80% of teens were getting their recommended doses of vitamin C—mainly from fruit punch, the researchers found.
“I would not advocate drinking fruit punch, but at least they are getting their dose of vitamin C from somewhere,” Burns said.
The researchers did not account for poverty and other factors that often distinguish less-healthy eaters and may explain their findings.
Burns added that there are several different ways to get the necessary nutrients.
“I think vitamin supplements are perfectly all right. I also think adding vitamin D to orange juice is fine. I am also of the opinion there are benefits that we don’t fully understand to eating whole foods such as fruit and vegetables and fish,” she said.