Teen Fatigue Causes: Top 5 Reasons Your Teen Is Always Tired
- New Pathways Programme
- Jun 21
- 6 min read
Updated: Jun 30
What are the most common teen fatigue causes?
If your teenager is constantly exhausted, you’re not alone. Many parents are searching for answers when it comes to teen fatigue causes — and the truth is, there’s rarely just one. From sleep issues to mental health challenges, understanding what’s behind your teen’s tiredness is the first step toward helping them feel better.
You’re not alone. Many mums come to us at New Pathways feeling overwhelmed and unsure how to help their child. The truth is, teen fatigue is very common, but it’s not always something they’ll just “grow out of.” Sometimes it’s a sign their body—or mind—is struggling and needs proper support.
Let’s walk through the five most common reasons teenagers feel so tired, and what you can do to support them.
1. They’re Recovering from a Virus—Even if It Was Months Ago
What You Need to Know About Post‑Viral Fatigue and Long COVID
Lots of teens bounce back quickly after an illness. But for some, a virus like glandular fever (mono), flu, or COVID-19 can trigger long-term fatigue that doesn’t go away. This is called post-viral fatigue, and it’s more common than people realise—especially since COVID.
In some cases, it develops into something known as Long COVID, where symptoms like tiredness, brain fog, headaches and aching muscles last for months. Even a mild initial illness can leave a teen feeling wiped out long after the infection has passed.
How to Spot It
They say they feel “tired all the time” no matter how much they rest
They crash after doing too much—even small things like walking to the shops
They can’t concentrate like they used to
Their mood has dipped, or they seem withdrawn
This kind of fatigue isn’t laziness—it’s their body asking for recovery and care.
2. They’re Not Getting the Sleep They Need (Even If They’re in Bed for Hours)
Why Sleep Gets Messy for Teens
Teenagers' body clocks shift during puberty, making it harder for them to fall asleep before 10 or 11pm. But school starts don’t change to match, so they’re constantly running on empty. Add in screen time, revision stress, and social pressures, and it’s no wonder they’re tired.
Even if your teen is spending plenty of time in bed, they may not be getting quality sleep—especially if their mind is racing, or they’re scrolling late into the night.
What to Watch For
Struggling to wake up for school
Napping during the day or on weekends
Feeling moody, forgetful or just “not themselves”
Saying they “can’t switch off” at night
Creating a calmer evening routine, limiting screen time before bed, and sticking to a regular schedule—even on weekends—can help reset their body clock over time.
Reference: Sleep Foundation: Teen Sleep Guidelines
3. They’re Missing Key Nutrients
Why Nutrition Matters More Than We Think
Busy teens often skip meals, snack on sugary foods, or follow restrictive diets without realising the impact on their energy levels. Low iron, vitamin B12, or vitamin D can all cause fatigue, weakness, and brain fog—and many teens are deficient without knowing it.
When to Get Checked
If your child looks pale, gets dizzy often, or seems unusually low on energy, it might be worth asking your GP for a blood test. Iron and vitamin D deficiencies are especially common in teenage girls.
4. Their Mental Health Might Be Taking a Toll
Fatigue Isn’t Always Physical
It’s heart-breaking to see your child lose their spark. Fatigue can be a symptom of emotional overwhelm, anxiety, or depression—especially if they’re dealing with school stress, friendship issues, or just feeling under pressure.
Some teens won’t come out and say they’re struggling. Instead, they might withdraw, sleep more, or avoid things they used to enjoy.
What to Look For
Loss of interest in hobbies or friends
Constant tiredness even after rest
Mood swings, irritability, or tearfulness
School refusal or low motivation
A kind, open conversation can go a long way. Let them know it’s safe to talk—and that help is available.
5. They May Be Developing Chronic Fatigue Syndrome (CFS/ME)
What Is CFS/ME?
CFS (also known as ME) is a serious condition that causes long-term exhaustion, poor concentration, pain, and unrefreshing sleep. It can start after a virus or build up slowly over time.
Around 1 in 100 teens may be affected. It’s more than “feeling tired”—CFS can be completely life-altering, especially without early support.
Typical Signs of CFS/ME
Feeling worse after doing too much (this is called Post-Exertional Malaise)
Waking up tired, no matter how long they sleep
Brain fog, memory slips, or trouble focusing
Dizziness, headaches, or sore throats that come and go
The good news is: recovery is possible. But the earlier it’s spotted and managed, the better the outcomes tend to be.
When Should You Be Concerned?
While occasional tiredness is normal for teens, you should speak to your GP if:
Fatigue lasts more than 3–4 weeks
They get worse after activity, rather than better
There’s a big change in mood or personality
They miss school, struggle to keep up, or stop doing things they enjoy
You sense something “isn’t right”
It’s okay to trust your gut. You know your child better than anyone.
How You Can Support Your Teen at Home
1. Listen and Believe Them
Fatigue is invisible. Your teen may look fine—but inside, they’re struggling. Let them know you hear them, believe them, and are here to help.
2. Track What’s Going On
Try using a fatigue tracker to monitor energy levels, sleep, symptoms, and school attendance. This helps spot patterns—and gives you something concrete to share with health professionals.📥 Download your free teen fatigue tracker [link to lead magnet or roadmap sign-up]
3. Focus on Gentle Progress, Not Pushing
If your child is living with post-viral fatigue or CFS, pushing them to “just try harder” can backfire. Gentle pacing, rest breaks, and prioritising energy can help them do more over time without crashing.
4. Look After Yourself, Too
Supporting a tired, withdrawn, or poorly child can be exhausting. Make sure you have support—whether that’s family, friends, a GP, or speaking to someone who understands what you’re going through.
Support That Makes a Difference
At New Pathways, we help teens recover from fatigue conditions like CFS, post-viral fatigue, and Long COVID—with a gentle, step-by-step approach that supports the whole family.
You don’t have to figure this out alone.
👉 [Book a free call] to talk about what’s going on with your child
👉 [Download your roadmap] for practical steps and supportive tool
Understanding Teen Fatigue Causes and What to Do
Helping your teen recover starts with understanding the most common teen fatigue causes. By spotting the signs early and offering the right kind of support, you can make a real difference in their wellbeing.
The key is to stay curious, stay calm, and take things one step at a time.
Your concern is valid. Your instincts matter. And help is available.
FAQs: Teen Fatigue and What Parents Need to Know
Q: How do I know if my teen’s tiredness is more than just being a teenager?
It’s normal for teens to sleep more during puberty, but if your child is always tired—even after rest—or their energy suddenly drops off, it’s worth looking deeper. Watch for signs like difficulty getting up, mood changes, or withdrawal. These could point to something like post-viral fatigue or CFS.
Q: What is post-viral fatigue and how long does it last in teenagers?
Post-viral fatigue is lingering exhaustion after an illness. It can last weeks or even months—especially following viruses like COVID-19 or glandular fever. In some cases, it may develop into Long COVID or CFS. Teens often describe feeling exhausted after doing even small things.
Q: Could my child have chronic fatigue syndrome (CFS/ME)?
If fatigue has lasted over three months and they’re also struggling with sleep, memory, and worsening after activity (PEM), they may have CFS. It affects up to 2% of teens. Early support and pacing strategies can make a big difference in recovery.
Q: What’s the best way to support a teen with fatigue?
Believe them. Keep track of their symptoms, help them prioritise rest, and avoid pushing too hard. Look into support from your GP and programmes like New Pathways that focus on teen recovery from fatigue in a gentle, structured way.
