There are three main reasons why the back to school season impacts sleep.
Firstly, during the summer vacation, Very Well Family notes that sleep routines in many families tend to be more relaxed than they would be the rest of the year. Children don't have to get up early in the morning and get ready for school, so they can stay up later in the evening and sleep in the next morning. But when school begins the summer routine suddenly ends. Kids have to get up and get around early, even though they cannot get to sleep at an earlier hour. Before they can adjust to the new routine, children may not be getting enough sleep, which can lead to fatigue and difficulty concentrating.
Secondly, DrugFree.org reports that for teenage students in particular, there are simply not enough hours in the day once school starts. Their internal clock is set later than that of either adults or younger children. Teens often find it hard to get to sleep before 11 PM, even if they want to. When school starts and an early morning schedule kicks in, they cannot get the 8 -10 hours of sleep they need and still be on time for classes the next day.
Thirdly, the beginning of the school year can be a stressful time, and stress affects sleep, according to Sleep.org. A child may be fearful of going back to school for a variety of reasons: bullying, homework, teachers, whether or not other kids will like them, unfamiliar surroundings. Worrying keeps the child awake at night, and a vicious cycle begins. Lack of sleep induces the body to increase the levels of stress hormones, which can make the child feel “wired". Consequently it is harder to fall asleep the next night, and the cycle begins all over again.