Lethargic Baby or Sleepy Baby?  Here's how to tell.
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Is Baby Lethargic Or Just Sleepy? What Parents Need To Know

True lethargy is an emergency. Here’s how to tell the difference.

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My son had a UTI when he was a little shy of three months old, so he was admitted to the hospital overnight for antibiotics after two emergency room visits. When we were finally able to bring him home — on top of being scared out of our minds and stressed with our new baby being in the hospital — we were told to keep a look out for signs of lethargy in our baby. If we did see signs of lethargy, we were supposed to bring him back to the hospital immediately. I kept asking them how to tell if your baby is lethargic or just sleepy, because I was worried I couldn’t tell the difference. When he’d spiked the high fever that brought us to the hospital in the first place, he seemed very out of sorts, extremely tired, and inactive. Was that lethargy? I didn’t want to miss this crucial sign that something was seriously wrong, but I was afraid that my untrained eyes wouldn’t really know the difference between sleepiness and actual lethargy. There is a definite difference, and it’s something that’s really important for parents to know how to watch for it, because if your baby is truly lethargic, you need to head to the emergency room, stat.

How to tell your baby is lethargic or just sleepy

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If your baby is truly lethargic, they’re difficult to rouse, says Dr. Danelle Fisher, vice chair of pediatrics at Providence Saint John’s Health Center in Santa Monica, California. Lethargy in babies is an emergency and you should rush them to the emergency room if you believe your baby is lethargic. “Babies who are in a deep sleep or sleepy will respond to stimulus, whereas lethargic babies will not,” she explains to Romper. “Lethargy is not the same as low energy, which is what 99 percent of parents describe as lethargy.” True lethargy is a dangerous state, and could be indicative of a lot of things, she adds.

“If your child has been sick and starts being extremely sleepy and not moving much or crying, that could be lethargy,” says Dr. Gina Posner, a pediatrician at MemorialCare Orange Coast Medical Center in Fountain Valley, California.

Lethargy can be a sign that something is seriously wrong. If you suspect your baby is lethargic, you should think of it as an emergency. Signs of lethargy, per Seattle Children’s Hospital, include:

  • Staring into space
  • They won’t smile
  • They hardly respond to you
  • They seem too weak to cry
  • They’re hard to wake up

“If your baby is lethargic, it is dangerous. We never use that word lightly — we are all taught that lethargy should be treated as a medical emergency," Posner says.

"Lethargy typically comes along with an illness." But Fisher is adamant that if your baby just seems tired, has low energy, or just isn't acting like themselves, it's not necessarily the same as lethargy.

What to do if baby is lethargic

At any age, lethargy is a dangerous sign and you should immediately take your baby to the emergency room if you notice it. “Typically your baby only gets true lethargy when they’re sick or if their hormone levels are off, but that’s more commonly found in the newborn stage,” says Posner.

You should also call the pediatrician if unusual sleepiness lasts for a while, or is accompanied by a fever or other signs of illness. As always, if you’re unsure or worried at all, call and ask your doctor for further guidance.


Dr. Gina Posner, a pediatrician at MemorialCare Orange Coast Medical Center in Fountain Valley, California

Dr. Danelle Fisher, FAAP, vice chair of pediatrics at Providence Saint John’s Health Center in Santa Monica, California

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