Recently economists looked at the relationship between pupils’ month of birth and their schoolperformance. It was found that among fourth graders, the oldest children scored on math and readingsomewhere between four and twelve percentile points better than the youngest children. That can beexplained as a “huge effect.” It means that if you take two intellectually    21      fourth graders with birthdaysat opposite ends of the cutoff date, the older student could score in the eightieth percentile,    22    theyounger one could score in the sixty-eighth percentile. That’s the difference between    23    for a giftedprogram or not. The economists said, “We do ability grouping early on in childhood. We have advancedreading groups and advanced math groups. So, early on, if we look at young kids, in kindergarten and firstgrade, the teachers are    24    maturity with ability. And they put the old kids in the advanced stream,where they learn better skills; and the next year, because they are in the higher groups, they do even better;and in the next year, the same thing happens, and they do even better again. The only country we don’tsee this going on is Denmark.” Denmark waits to make selection decisions until maturity differences byage have      25   . This is because they have a national policy where they have no ability grouping untilthe age of ten.

        When he moved from South Africa to New York City, Norman Rosenthal, a psychiatrist, noticed he felt more depressed during the cold, short days of the city’s winters than he had in his home country. Years later, he published the first paper to scientifically name the winter blues: Seasonal Affective Disorder (SAD). Subsequent studies have found that the seasonal depression affects those in northern latitudes more and that about 10 percent of SAD sufferers have symptoms in the summertime instead.          The most commonly reported symptoms of winter depression are hypersomnia, the desire to sleep more than usual, as well as an increased appetite and lack of interest in things. According to experts, most people experience symptoms in young adulthood, but SAD can begin at any stage of life. The condition also varies by sex. About three times as many women as men get SAD.

       But why does less daylight make some people clinically depressed? One leading theory is that the change in daylight disrupts our bodies' release of melatonin, a hormone the brain releases every night to promote sleep. As the supply of daylight dwindles in winter, melatonin may wear off later. That means in the morning the body is still in a state of biological night. As for summer SAD, triggers might include the heat and humidity. Instead of feeling lethargic, summer SAD patients more often feel irritable and agitated.

       Experts say a professional diagnosis is a crucial first step toward treatment and self-diagnosis is not suggested. One common treatment is sitting in front of a bright box of light for 30 minutes to signal to the body that it’s time to wake up. But the drawback to light boxes is that they only work on the day that you use them, so you need to use them daily. Another treatment that may have longer lasting benefits is Cognitive Behavioral Therapy (CBT), a form of talk therapy. As negative thinking tends to breed negative emotions, CBT aims to encourage more neutral thoughts. For example, “I hate winter” might be reframed as “winter isn’t my favorite season, but I still find things to enjoy.” Moreover, finding wintertime hobbies may also help. People with SAD often have hobbies that are summer specific, such as growing gardens or beach going. Instead of hibernating under a blanket, people are encouraged to find indoor hobbies, such as knitting, reading, or going to the gym, to boost their mood. Whether using light or talk therapy, there is no reason to not seek mental health treatment, even if symptoms are only present for a few months out of the year.