Q: My 14-year-old daughter goes to bed each night around 10 p.m. Some nights she complains that she cannot fall asleep until hours later. Although she wakes up and says she isn’t tired, she does sleep in on weekends. I’m worried it’s affecting her ability to concentrate in school. Any help?

A: Lots of children your daughter’s age have trouble falling asleep at night. Though one might say your daughter has bouts of insomnia, in many cases, the reason for sleep challenges can be traced back to habits a child has developed that interfere with good sleep. Less often, it may be a sleep disorder.

Many teens don’t get the sleep they need. To stay healthy, teenagers need about eight to 10 hours of sleep each night. Sleep is important; it fights stress, improves mood and provides energy. When teens are well-rested, they can concentrate, learn, listen and think better than when they’re tired. That can improve school performance.

Sleep issues plague many teenagers, with about 70% of high school students reporting inadequate sleep on school nights. One of the big reasons is that the body’s internal clock shifts during the teen years. In the preteen years, the hormone melatonin, which signals to the body that it’s time to sleep, is released into the bloodstream earlier in the evening. In most teens, melatonin levels don’t rise until about 10:30 or 11 p.m., so they aren’t sleepy before then. But going to bed at that time means teens should ideally sleep until about 7:30 or 8 a.m. This isn’t an option for many because of school start times.

Some teens tend to show a preference for the late evening hours. They are the most energetic, intellectually productive and creative in the late evening. This is normal. For those with “night owl” tendencies, however, it is important to provide lots of light exposure upon waking in the morning and to dim the lights around the house during evening hours.

One of the most important things teens can do to sleep well regularly is to set a consistent wake-up time and build a sleep schedule around it. The wake-up time should be within about a two-hour window every day. This allows the body’s internal clock to run smoothly and avoid the difficulty of trying to get up Monday morning at 6 a.m. after sleeping in until noon on the weekends.

Picking a reasonable bedtime and sticking to it can be useful, too. When teens get up at the same time every day, they will get sleepy around the same time every night.

Your daughter should stay away from soda pop, sugar, caffeine and big meals two to three hours before going to bed. She should exercise, but do it at least two hours before bedtime. And she should avoid naps during the day.

Electronic devices and screens often disrupt sleep. Avoid distractions by keeping TVs and computers out of bedrooms. Cellphones should be turned off at bedtime and stored outside the bedroom. Keep bedrooms cool, dark and quiet at night.

Be mindful of how homework, extracurricular activities and after-school jobs can affect goals you set. If activities are too time-consuming, it may lead to a more significant amount of lost sleep. If your teen has a job, consider limiting it to no more than 15 hours a week with hours that do not interfere with sleep opportunity. Then, it’s likely she’ll still have enough time for other activities without sacrificing sleep.

Work with your local school district to advocate for later school start times in accordance with American Academy of Pediatrics and American Academy of Sleep Medicine recommendations that school should not start before 8:30 a.m. for middle and high school.

If she is having persistent problems falling asleep on a regular basis, contact a sleep specialist.

— Robin Lloyd, M.D., Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota

Mayo Clinic Q&A is an educational resource and doesn’t replace regular medical care. Email a question to MayoClinicQ&A@mayo.edu.