I see many kids each month who complain of being too tired. Parents often fear the worse, such as low iron or even cancer. There are many things to consider, but there are a few very common reasons that could explain why a child or teen is tired. I'm also including some less common things that make kids feel tired, but are common worries of parents. Always remember that common is common. Serious causes of being tired will not happen with fatigue as the only complaint.

Here are 10 reasons a child or teen is tired:

1. Not enough exercise

Strenuous aerobic exercise helps our bodies get healthy, quality sleep. Better quality sleep improves our performance, both physical and mental.

If you lay around, you tend to feel more relaxed, lazy and tired. Getting up and moving can help.

Many kids sit all day at school, then come home to sit more doing homework, watching tv, or playing video games.

Limit time on screens, especially before bedtime. We need to encourage kids to get up and move, ideally outside.

Make it fun!

• Take a walk to a park, then play

• Play catch

• Go on a bike ride

• Swim

• Join a sports team

• Play frisbee

• Golf

• Go bowling

• Dance

• Try yoga -- there are many online videos to get you started

Several of these ideas you can do with your kids. Make it a family goal to be active together! It models the healthy habits you want your kids to live.

2. Celiac disease

Celiac disease is an autoimmune disease in which people can't eat gluten (a protein found in wheat, barley and rye) because it will damage their small intestine. This can lead to malnutrition and anemia (low red blood cell counts). Symptoms vary, but often include abdominal pain, diarrhea, constipation, fatigue and bloating. In kids it can affect puberty and growth. Celiac disease can run in families.

There are a lot of people who say they feel healthier when they avoid gluten for non-celiac gluten sensitivity. These people have symptoms that are found in celiac disease, such as abdominal pain, bloating, diarrhea, constipation, headaches, bone or joint pain, and chronic fatigue when they have gluten in their diet, but do not test positive for celiac disease. It is not clear what the etiology of this is, but removing gluten seems to improve symptoms.

It's uncommon for kids to have fatigue as the only symptom of celiac disease, but if you are worried about their symptoms, schedule a visit with their physician to discuss it as a possibility.

A quick warning...

Do not remove gluten from their diet without talking to your doctor. Gluten in the diet is needed for testing, which is needed to confirm celiac disease.

Celiac disease is important to diagnose and treat due to chronic issues that can occur from long-term damage to the intestines. If a child doesn't have a true diagnosis, it is more likely they will not remain compliant with the diet changes that are required.

3. Depression

We often think we would recognize a depressed child or teen. We picture them crying often or appearing sad, but this is not necessarily how they appear. Yes, they can cry and appear sad, but sometimes they don't.

Depression doesn't always look like you'd think.

Sometimes parents think their child is angry. Or parents are mad because a teen stops trying at school. The child might get into fights.

Common symptoms of depression:

1. Sadness, crying and tears

2. Losing interest in things they usually enjoy

3. Appearing angry or irritable

4. Boredom and apathy

5. Isolation from friends and family

6. Extreme sensitivity

7. Headaches, stomach aches, and other ill type symptoms

8. Low self-esteem or guilt

9. Poor concentration

10. Change in eating patterns - either more or less

11. Low energy

12. Falling grades

13. Change in sleeping patterns - either more or less

14. Self harm (cutting or other behaviors)

15. Talks of suicidal thoughts or intent

If you think your child is depressed, please get professional help. Sadly, depression is a fairly common underlying reason for kids to be tired.

4. Thyroid problems

Thyroid problems are relatively common and can be present at birth or develop later in life.

Hypothyroidism occurs when the thyroid gland does not make enough thyroid hormone. About 5% of people over 12 years of age has hypothyroidism.

People with hypothyroidism might feel depressed, be tired, have poor focus, and become forgetful. They might gain weight or have slowed growth. They might feel colder than others or have constipation. Sometimes they'll develop a swelling in their neck called a goiter.

Most of these are very common symptoms that are not specific to thyroid problems. Having some of them does not necessarily mean that there is a problem with the thyroid. If there are several of these symptoms, it's relatively easy to screen for thyroid problems with a blood test.

Schedule an appointment to talk to your pediatrician if you're concerned about a thyroid problem.

5. Too much sugar

Although the body needs sugar for energy, eating too much refined sugar can cause weight gain, chronic disease and sugar crashes. Excess weight can make it harder to exercise and sleep, both of which help us not feel tired.

Encourage kids to eat a healthy balance of fruits, vegetables, proteins, and complex carbohydrates.

Limit the juices, candies, and other high-sugar / low nutrition foods. I know this is easier said than done when kids beg and cry for candy. It's even harder to limit when kids grab their own snacks.

Keep easy to eat healthy snacks available as much as possible. Don't buy the junk. Kids will get plenty of it outside the home. If it's not at home, they won't grab it.

6. Caffeine

Most adults have grabbed a caffeinated beverage to help ward off fatigue, but caffeine can lead to poor sleep and more tiredness. It can become part of an unhealthy cycle.

Kids don't need caffeine. If they do have it, it should be before noon. Caffeine can stay in your body for about 8 hours and keep you from sleeping.

Children under 10 years of age should not have caffeine due to jitteriness, irritability, and other side effects. It's recommend that kids who are 10 - 12 should get no more than 85 mg per day. Teens should have 100 mg or less. Up to 400 mg of caffeine a day appears to be safe for most healthy adults.

Mixing caffeine with certain medicines or alcohol can increase its problems.

7. Anemia

Anemia is a low red blood cell count.

Our red blood cells bring oxygen to the cells of our body, and when the levels are low we can feel tired. Other symptoms are irritability and pale skin coloring. Often there are no symptoms with mild anemia.

There are many causes of anemia. Blood work can help to identify anemia and its causes. Treatment depends on the cause.

If you're worried about anemia, schedule an appointment with your pediatrician. A history and exam will be needed to determine if labs are indicated.

8. Insomnia

It makes sense that if you don't sleep enough, you'll be tired. When people have insomnia, they do not sleep enough hours.

There are many causes of insomnia, but all can lead to insufficient sleep. Addressing the underlying cause is important.

1. Anxiety and depression (see above)

2. Screens (see below)

3. Circadian rhythm changes

4. Allergies or other causes of nasal congestion

5. Pain

6. Gastroesophageal reflux

7. Restless leg syndrome

8. Some medications and caffeine

9. Exercise too late in the evening

10. Nicotine (growing in popularity among kids due to vaping)

If your child is struggling to sleep, schedule an appointment to discuss potential reasons and treatments.

9. Sleep apnea

Sleep apnea happens when a person stops breathing during sleep. It's usually caused by something blocking the upper airway. You might hear snoring followed by pauses in the breathing pattern, gasps, or choking sounds.

Because the airway is obstructed, oxygenation levels can fall briefly. This triggers the brain to wake up to open the airway. When this happens repeatedly throughout the night, sleep quality is affected. A person wakes feeling tired.

Enlarged tonsils or adenoids and obesity are common causes of sleep apnea. If you think your child has sleep apnea, talk to your child's pediatrician.

10. Screen time

The light emitted from televisions, computers, tablets, and smart phones trick our brains into staying awake.

When kids are on a screen up until bedtime, their brain is not yet ready to go to sleep. This leads them to stay up too late, which makes them too tired the following day.

Dr. Craig Canapari discusses the problems with screens and sleep in Prevent Sleep Problems in Kids: Keep Technology Out of The Bedroom.

Not enough sleep is the common thread to many of these.

Not enough sleep is the #1 reason I find for kids being tired. They need more sleep.

Studies show that many of us just don't sleep enough. It's important for kids to get adequate amounts of sleep. If your child is tired and is not able to sleep sufficiently, talk to your pediatrician about ways to improve sleep and decrease fatigue.