Growing pains are not a myth, but they are badly named. The aching legs that wake children at night are a well-documented phenomenon affecting roughly a quarter to over 40 percent of kids, depending on how the condition is defined. What is mythical is the explanation baked into the name: there is no evidence that growing causes the pain. The term has stuck around for nearly two centuries despite the fact that researchers have repeatedly shown growth spurts play no part in the condition. The pain is real, but the science behind it points in directions that have little to do with bones getting longer.
What Growing Pains Actually Feel Like
The typical picture is a child between the ages of about three and twelve who complains of deep, aching leg pain in the evening or at night. The pain usually hits the thighs, calves, or the area behind the knees. Between 80 and 90 percent of affected children describe the discomfort as bilateral, meaning both legs hurt at the same time. Older kids often call the sensation severe or cramping, while parents of younger children report their kids crying from the intensity. Episodes last anywhere from a few minutes to a few hours, and then the child wakes up the next morning perfectly fine, with no limp or visible swelling.1PubMed Central. Growing Pains: When to Be Concerned
That pattern of real pain with zero physical findings is part of what makes growing pains so frustrating for families and clinicians. There is no blood test, no X-ray finding, no swollen joint. The diagnosis is one of exclusion: if a child’s legs hurt at night, the exam is normal, and nothing else explains it, it gets labeled growing pains.
Why Growth Has Nothing to Do With It
The name dates back to the 1820s, when a French physician attributed limb pain in children to the process of growing. The idea has intuitive appeal, but it does not hold up. Studies have found no relationship between the timing of growth spurts and episodes of pain. Children in the fastest phases of growth are not more likely to have symptoms, and children growing slowly can have terrible episodes. A widely cited review in the BMJ put it plainly: although the term has been used for more than 180 years, it has proved to be a misnomer.2BMJ. Growing pains
A scoping review published in Pediatrics came to the same conclusion, describing “growing pains” as an historical term with appeal in the English lexicon but no evidence that it causally relates to growth.3Pediatrics. Defining Growing Pains: A Scoping Review The name persists largely because nothing better has replaced it. Pediatric researchers have occasionally floated alternatives like “recurrent nocturnal limb pain of childhood,” but none has caught on with parents or doctors.
How Common Growing Pains Are
Prevalence estimates vary widely, mostly because researchers cannot agree on exactly what counts. A large study of Danish preschool children found that anywhere from 24 to 43 percent of kids aged three to six experienced growing pains, depending on which definition was applied. Pain episodes in those children most commonly happened one to three times per week and centered in the lower legs.4PubMed Central. Growing pains in Danish preschool children: a descriptive study The prevalence tended to climb with age within that preschool window, and household income or other socioeconomic factors did not consistently predict who was affected.
Other studies have reported slightly different ranges, but the general picture is consistent: growing pains are among the most common musculoskeletal complaints in childhood. They are not rare, and they are not something a small handful of sensitive kids experience. They are an ordinary part of growing up for a significant share of children, which makes the lack of a clear cause all the more remarkable.
A Diagnosis Without Agreed-Upon Rules
One reason the research landscape is messy is that there is no universally accepted set of diagnostic criteria. A scoping review published in BMJ Open identified 15 unique sets of diagnostic criteria used across the literature, with limited consistency and sometimes outright conflict between them.5BMJ Open. Assessments, diagnostic criteria and outcome measures for growing pains and persistent pain in the presence of restless leg syndrome in children: a scoping review Some criteria require pain in both legs; others allow one-sided pain. Some insist on an age range of three to twelve; others do not specify. Some exclude children who limp; others do not mention limping at all.
This lack of agreement means that a child who qualifies as having growing pains under one researcher’s definition might not under another’s. It also means prevalence studies are comparing slightly different conditions, which partly explains the wide range of estimates. The field has been trying to tighten up the criteria for years, but the condition’s benign reputation has probably slowed progress. Growing pains are not dangerous, so the urgency to define them precisely has not been as strong as it might be for a more serious condition.
What Might Actually Be Causing the Pain
If growth is not the culprit, what is? Several theories have been explored, and the honest answer is that no single explanation has won out. The evidence points toward a combination of factors rather than one neat mechanism.
Lower Pain Thresholds
One of the more compelling findings is that children with growing pains seem to process pain differently. A study comparing affected children to matched controls found that the pain threshold at standard pressure points was significantly lower in the growing-pains group. Those children also had a greater number of tender points in response to a set amount of pressure, a pattern that resembles what is seen in adults with non-inflammatory pain syndromes.6PubMed. Decreased pain threshold in children with growing pains
A separate study using sensory testing confirmed a similar picture: children with growing pains had heightened responses to cold, vibration, and deep pressure compared to controls. The increased sensitivity showed up beyond just the legs, suggesting a more generalized shift in how the nervous system handles sensory input rather than a local problem in the limbs.7PubMed Central. Somatosensory test responses in children with growing pains This does not mean affected children are imagining things. It means their nervous systems may amplify signals that other children barely notice.
Physical Activity and Body Composition
Parents often observe that growing pains seem worse on days when their child has been especially active, and research supports that connection. A cross-sectional study of children in Chongqing, China, found that increased exercise was positively associated with both pain frequency and pain intensity. Being underweight and having cold lower extremities were also linked to more frequent episodes.8PubMed Central. An exploration of clinical features and factors associated with pain frequency and pain intensity in children with growing pains The exercise link does not mean activity causes the condition, but it may help trigger episodes in children who are already susceptible. Interestingly, growing pains are typically described as not being caused by activity and not producing a limp, which distinguishes them from overuse injuries. The pattern seems to be that a busy day of running around can prime the system for a painful night, even though the pain itself does not appear during the activity.
Blood Flow Changes
Because growing pains share some features with migraine headaches, one older theory proposed that changes in blood flow to the affected limbs might be involved. A systematic review that examined this hypothesis found no evidence to support it.9PubMed Central. Growing pains: What do we know about etiology? A systematic review The vascular theory remains unproven and has largely fallen out of favor, though the comparison to migraine is interesting because both conditions involve episodic pain without structural damage.
The Vitamin D Connection
One area that has generated real clinical interest is the relationship between growing pains and vitamin D levels. A study of 120 children with growing pains found that about 87 percent had insufficient vitamin D. After supplementation, average vitamin D levels roughly tripled and pain scores dropped substantially.10PubMed Central. Are Growing Pains Related to Vitamin D Deficiency? Efficacy of Vitamin D Therapy for Resolution of Symptoms
A pilot cohort study found similar results: children with growing pains who received vitamin D supplementation showed significant reductions in pain intensity after three months, with further improvement continuing over two years. Bone mineral markers also improved alongside the pain reduction.11PubMed. Significant association among growing pains, vitamin D supplementation, and bone mineral status The Chongqing study mentioned earlier also found that maternal vitamin supplementation during pregnancy was associated with lower pain frequency in children, adding another piece to the nutritional puzzle.8PubMed Central. An exploration of clinical features and factors associated with pain frequency and pain intensity in children with growing pains
This does not mean vitamin D deficiency is the cause of growing pains. Vitamin D insufficiency is extremely common in children generally, so finding it in a group of kids with leg pain does not prove the two are linked. But the supplementation studies are suggestive enough that checking a child’s vitamin D level and correcting any deficiency is a reasonable step, even if it turns out not to be the whole story.
When Growing Pains Might Actually Be Restless Legs Syndrome
There is a growing body of research suggesting that some children diagnosed with growing pains may actually have restless legs syndrome, or a condition closely related to it. The two share several features: both tend to start between ages three and twelve, both involve unpleasant sensations in the legs that worsen in the evening or at night, both come in intermittent episodes that can be relieved by movement, and neither produces abnormal findings on physical exam.12PubMed Central. Restless legs syndrome and growing pains in childhood: understanding the link
The key distinguishing feature is the urge to move. Restless legs syndrome is defined by an uncomfortable sensation that creates a strong compulsion to move the legs, with relief on movement. Growing pains are typically described as deep aching without that specific urge. But in a young child who cannot articulate exactly what the sensation feels like, the distinction can be nearly impossible to make.
Sleep studies have added an interesting wrinkle. One study found no differences in standard sleep-lab findings between children with growing pains and controls.13Sleep. Some Children with Growing Pains May Actually Have Restless Legs Syndrome But a larger study found that children with growing pains were about three times more likely to have periodic limb movements during sleep, a hallmark of restless legs syndrome, compared to children without growing pains.14PubMed. Growing pains and periodic limb movements of sleep in children That finding supports the idea that at least a subset of growing-pains cases may sit on the same spectrum as restless legs syndrome. The clinical implications are meaningful because restless legs syndrome in children can sometimes be treated with iron supplementation when ferritin levels are low, a specific intervention that would not occur to anyone thinking of the problem as generic “growing pains.”
What Actually Helps
Because the cause is uncertain, treatment for growing pains has traditionally been reassurance and comfort measures. Most pediatricians advise massaging the affected legs, applying a warm cloth or heating pad, and giving a standard dose of an over-the-counter pain reliever if the child is very uncomfortable. Stretching the leg muscles before bed is another commonly recommended strategy, though the evidence for it is mostly anecdotal rather than trial-based.
Correcting vitamin D deficiency is probably the most evidence-backed intervention beyond basic comfort care, given the studies showing pain reduction after supplementation. If your child has frequent episodes, asking your pediatrician to check a vitamin D level is reasonable and straightforward. Beyond that, paying attention to patterns can help: some parents notice that episodes are worse after unusually active days, and while you obviously should not discourage a child from being active, knowing the trigger can help you prepare with preemptive stretching or a warm bath before bed.
For the subset of children whose symptoms may overlap with restless legs syndrome, a ferritin level check is worth discussing with your doctor. Low iron stores are treatable and can drive restless-legs symptoms in children just as they do in adults.
When the Pain Is Not Growing Pains
Because growing pains are a diagnosis of exclusion, the more important clinical question is often what the pain is not. Several features should prompt further investigation rather than reassurance:
- Pain in one leg only: While some studies have found that growing pains can occasionally be unilateral, persistent one-sided pain raises concern for other conditions such as stress fractures or bone tumors.
- Pain during the day or during activity: Classic growing pains do not cause a child to limp or stop playing. Daytime pain that limits function needs a different workup.
- Swelling, redness, or warmth: Any visible inflammation around a joint or along the leg suggests a condition like juvenile arthritis or infection rather than growing pains.
- Fever or weight loss: Systemic symptoms alongside limb pain should always prompt medical evaluation.
- Worsening over time: Growing pains are episodic, not progressive. Pain that steadily gets worse week to week is not following the typical pattern.
A normal physical examination and normal lab work on the days between episodes are hallmarks of growing pains. If either is abnormal, the diagnosis should be reconsidered.1PubMed Central. Growing Pains: When to Be Concerned
The Cost of Dismissing Childhood Pain
One underappreciated aspect of growing pains is how the label itself can become a barrier. Because the name sounds benign and because the condition is self-limiting, there is a tendency to wave off a child’s complaints. For most kids, the pain really does resolve on its own by the teen years. But for a meaningful minority, episodes are frequent, severe, and disruptive to sleep and family life. Pediatric pain-related conditions as a whole are associated with substantial healthcare costs, estimated at roughly $11.8 billion in incremental spending per year in the United States alone.15PubMed Central. Health care expenditures associated with pediatric pain-related conditions in the United States
Growing pains sit in an awkward spot: common enough to be considered normal, painful enough to wake a child screaming, and mysterious enough that the medical name for the condition is known to be wrong. The research is slowly moving toward a more nuanced understanding. Evidence on pain processing, vitamin D, restless legs overlap, and activity patterns is filling in pieces of what is clearly a puzzle with multiple contributing factors rather than one clean cause. For parents managing a child with aching legs at two in the morning, the most useful thing the science currently says is that the pain is real, it is not dangerous, and it is not caused by growing. Beyond that, checking vitamin D, watching for red flags, and considering the possibility of restless legs syndrome are the most concrete steps available while researchers continue sorting out what is actually going on.