When you’re living with Rett syndrome or caring for someone with this condition, it can sometimes feel like the world only notices the things you can see—like hand movements, physical changes, or walking difficulties. But so much of Rett happens quietly, beneath the surface. These are the symptoms no one talks about at first glance, the ones that don’t always show up in pictures or at the doctor’s office, but that affect daily life just as much as the obvious signs.
For parents, understanding these “invisible” aspects of Rett syndrome can make it easier to comprehend what your child is experiencing. And for people with Rett, it can be comforting to know that the things you feel—even if others can’t see them—are very real.
1. Subtle early development slowdown
Early signs of Rett syndrome can be subtle. Sometimes, babies grow and develop typically for a while, and then their progress slows down in ways that aren’t immediately apparent. Eye contact may fade slightly, or there may be a decrease in interest in toys. Parents may not notice right away—especially since every child develops at a different pace.
In the earliest stage of Rett (Stage I), “symptoms … may be somewhat vague.”
2. Low muscle tone (hypotonia)
Some children with Rett have low muscle tone, which can make their bodies feel softer or “floppier” than expected. It’s not always obvious, though—especially if your child compensates in other ways. A pediatrician may be the first to notice it during an examination.
Low muscle tone is one of the early signs families might see, alongside reduced interest in play and eye contact.
3. Quiet language awareness
Speech may fade, but that doesn’t mean understanding disappears. Many kids and teens with Rett syndrome still process and respond to what’s happening around them—even if they can’t put their thoughts into words. You might see recognition in a smile, a sparkle in the eyes, or excitement when a favorite song plays.
A 2024 review found that while expressive language (speaking) is often very limited, receptive skills (understanding) can remain, showing up in subtle emotional responses.
4. Anxiety and emotional waves
Sometimes a child with Rett may cry, scream, or seem anxious without an obvious reason. These episodes aren’t always connected to what’s happening in the moment—they can come from inside the brain itself. For families, this can be confusing and heartbreaking.
According to the Mayo Clinic, irritability and sudden crying may “begin suddenly, for no apparent reason, and last for hours,” often tied to anxiety.
5. Sleep struggles
On the outside, your child may look rested during the day. But Rett often comes with nighttime wake-ups, irregular sleep cycles, or trouble falling asleep. Families may be the only ones who truly see how exhausting this can be.
6. Different responses to pain
Parents may notice that their child doesn’t react to pain the way others do. A bump, cut, or even something more serious might not trigger the expected cry. This doesn’t mean the pain isn’t there—it just shows up differently in Rett.
The NHS lists “diminished response to pain” as one of the supportive features seen in Rett.
7. Cold hands and feet
It may seem small, but hands and feet that are always cold—or even bluish—can be a sign of deeper circulatory changes in Rett. Parents often notice this during cuddles or when dressing their child, but outsiders rarely see it.
This symptom is sometimes called a “peripheral vasomotor disturbance.”
8. Unexpected laughing or screaming spells
Sometimes laughter or screaming comes at moments that don’t seem to fit the situation. These episodes can feel confusing, but they’re part of how Rett affects the nervous system. It’s not misbehavior—it’s a symptom.
9. Breathing changes
Breathing irregularities—like holding the breath, breathing very quickly, or even swallowing air—often happen when a child is awake. Unless you’re there in the moment, these can go unnoticed, but they can be scary when they happen.
Why This Matters
“Invisible” doesn’t mean unimportant. These symptoms are very real, and they shape daily life in powerful ways. By naming and understanding them, parents can better support their children, people with Rett can feel seen, and doctors can approach Rett with more empathy.