Oftentimes, my teenage patients complain of extreme tiredness or fatigue – especially during the school year. Meet some of my tired patients:

Patient 1: A 16-year-old female fainted when she got out of bed. For months, she felt dizzy and lightheaded when changing from lying to standing. She also felt sleepy during the day. She used to run track at school but couldn’t anymore.

Patient 2: A 22-year-old female complained of seven months of extreme fatigue. She felt tired but her sleep was unrefreshing. She also had muscle aches, dizziness upon standing, and headaches. Recently she tried to take the MCAT, couldn’t concentrate, and stopped during the first section. Afterward, she was completely exhausted and couldn’t get out of bed for three days.

Patient 3: A 14-year-old boy was tired constantly. He just started high school and struggled with the earlier start time. In school, he had trouble concentrating and fell asleep during history. At home, he was irritable and argumentative.

Nine times out of 10 their lack of sleep is related to normal teenager life — too much of one thing and not enough of another. But occasionally, the problem can be linked to a serious medical issue, such as obstructive sleep apnea, restless legs syndrome, and narcolepsy.

For example, Patient 1 has postural orthostatic tachycardia syndrome (POTS), a condition in which too little blood flows to the brain, causing fainting or lightheadedness when changing from lying down to standing up. Patients experience a rapid and uncomfortable increase in heart rate when upright. They can have sleep problems, weakness, sweating, and trouble concentrating. POTS is most common in females ages 15 to 50. Although the cause is unknown, it often starts after a viral illness, surgery or injury. Symptoms can be mild or severe.

A tilt-table test is often done to diagnose this condition; heart rate and blood pressure are monitored when a person is tilted from lying to standing. POTS is sometimes seen in teenagers with other diagnoses, including Ehlers-Danlos syndrome, inflammatory bowel disease and myalgic encephalitis/chronic fatigue syndrome (ME/CFS). POTS patients may be prescribed medications to support the circulatory system (for example, fludrocortisone, midodrine, ivabradine) or to support the autonomic nervous system (beta blockers, pyridostigmine). Additional treatments include increasing water and salt intake, wearing compression stockings, and slowly increasing exercise. Psychotherapy and support groups can help. POTS symptoms usually improve over time.

Patient 2 has ME/CFS, a complex illness that is potentially disabling. The diagnosis is made by:

  • The inability to do previous activities for at least six months.

  • Worsened symptoms after physical or mental activity.

  • Sleep that is unrefreshing.

Individuals with ME/CFS can have POTS, too. Other symptoms include problems with thinking and memory, joint pain, headaches, sore throat, and sore lymph nodes.

Although the exact cause is unknown, ME/CFS sometimes runs in families. ME/CFS is more common in females and more common in older people but teens can be affected. No single test makes the diagnosis. Like with POTS, treatment includes exercise, psychotherapy, and support groups. Teens usually partially or fully recover within five years.

Patient 3 needs more zzz’s. As a matter of fact, so do most teens. Some of our teens are terribly tired due to stress.

Teens need eight to 10 hours of sleep each night to function at their best. According to the National Sleep Foundation, only 15% of teens reported sleeping 8½ hours on school nights. It may be all in their heads: Teens’ brains release the sleep-promoting hormone melatonin later at night than do the brains of younger children and adults. Exposure to electronics at bedtime also interferes with sleep. So encourage teens to turn off their devices at least an hour before.

Rima Himelstein is an adolescent medicine specialist at Nemours/Alfred I DuPont Hospital for Children.