The Merlin sleep suit is a popular sleep aid that helps babies sleep better by providing a snug, weighted feel. While it can be very effective, there are some situations where a Merlin suit may not be appropriate. In this comprehensive guide, we’ll discuss when and why you may want to avoid using a Merlin sleep suit with your baby.
If your baby can roll over
One of the most important times to stop using a Merlin sleep suit is as soon as your baby shows signs of being able to roll over. The Merlin suit is designed to keep a baby who cannot yet roll in the back sleep position. Once a baby can roll, continuing to use the swaddle up sleep suit increases the risk of suffocation or entrapment issues. According to the American Academy of Pediatrics, any type of swaddle or restrictive sleep clothing should be avoided as soon as a baby exhibits rolling capabilities.
Signs that your baby is approaching rolling over include:
- Your baby can turn to the side while laying on their back
- Your baby can lift and turn their head from side to side easily while on their back
- Your baby pushes up onto their forearms while on their stomach
- Your baby arches their back and lifts their chest off the ground while on their stomach
As soon as you notice any of these pre-roll signs, it’s time to transition your baby out of the Merlin suit and into a regular sleep sack or wearable blanket. Using a Merlin suit too long past the first roll-over puts your baby at risk.
If your baby is over 12 months old
The Merlin sleep suit is only intended for use up until 12 months of age. The makers of the suit, Merlin Magic Sleepsuit, explicitly state that it should be stopped by 12 months at the very latest. There are several good reasons to transition out of a Merlin suit by a baby’s first birthday:
- Older babies have more mobility and rollover capability, increasing suffocation risks
- Toddlers should not have their movement restricted at night
- The Merlin suit may interfere with a toddler’s ability to self-soothe and find a comfortable sleeping position
- Many parents report it becomes difficult to keep a toddler in the Merlin suit as the child becomes more aware and resistant
For these reasons, it’s best to switch your baby to a regular wearable blanket or sleep sack without weight by 12 months old. The Merlin suit is not tested or approved for safety beyond a baby’s first year.
If your baby seems uncomfortable
Babies often go through periods of resisting the Merlin suit, especially as they become more mobile. Signs your baby may be unhappy or uncomfortable in their Merlin suit include:
- Fussiness when putting on the suit
- Attempts to break free of the suit while wearing it
- Difficulty settling to sleep while wearing the suit
- Waking up frequently while wearing the suit
If your baby has used the Merlin sleep suit successfully but then suddenly starts fussing, it may be time to try transitioning to a wearable blanket or other sleep aid. Be sure to choose a transition product that allows for more freedom of movement while still providing some sensory feedback. Watch your baby’s cues closely and be willing to stop using any sleep aid that seems to cause significant distress.
In warm weather
The Merlin sleep suit is made of thick, heavyweight cotton material and is designed to provide a lot of warmth. This can be great for cold weather but problematic when temperatures start to rise. Most babies will be uncomfortable and upset trying to sleep in a Merlin suit in a warm room of 75°F or hotter. Here are some signs your baby may be getting too hot in their Merlin suit:
- Sweating excessively
- Flushed, red cheeks
- Waking up frequently
- Difficulty falling asleep
- Fussiness
If you notice these overheating clues, try dressing your baby in only a diaper and sleep sack in the Merlin suit. If your baby still seems hot, it’s best to transition to only a lightweight sleep sack or wearable blanket. You can always add layers like footed pajamas or swaddle wraps when it’s cooler.
With other swaddling products
The Merlin sleep suit is designed to provide a snug, swaddle-like feeling for babies. Using additional swaddling products in conjunction with a Merlin suit is unnecessary and potentially hazardous. Other swaddles like the Miracle Blanket, SwaddleMe wraps, and traditional swaddle blankets should not be worn over or under a Merlin suit.
Combining swaddling methods can lead to dangerous overheating issues. It also further restricts your baby’s mobility, which increases the risk of hip dysplasia. If your baby seems to need additional soothing beyond the Merlin suit, look for other alternatives like a sound machine, pacifier, or fingering crib toys.
For daytime naps
While Merlin suits are often used at night to help baby sleep longer stretches, they are not recommended for naps. During the day, it’s best to let your baby nap in regular pajamas or just a diaper. There are a few reasons to avoid Merlin suit use for naps:
- Naps allow baby time to move freely and develop gross motor skills
- The Merlin suit may make baby sleep too long, interfering with nighttime sleep
- Daytime Merlin use can become a crutch baby relies on
- Babies need freedom of movement to practice rolling during awake times
If your baby relies on the Merlin suit to fall asleep but then fusses while wearing it for a daytime nap, it’s a sign they need more freedom of movement for quality rest during daytime hours.
During tummy time
Babies should not wear a Merlin sleep suit during tummy time. Doctors recommend supervised tummy time beginning as early as a few days old. Laying your baby on their stomach while awake and supervised helps strengthen neck and back muscles critical for development. The Merlin suit makes tummy time positioning difficult and prevents your baby from moving their arms and legs to practice pushing up. Always remove any swaddle or sleep suit during tummy time.
If your baby develops a fever
It’s important to avoid overheating or bundling a baby with a fever. If your baby develops a fever over 100°F while wearing a Merlin suit, immediately remove the suit and dress them only in a diaper or very lightweight clothing. The extra warmth from the weighted suit can cause your baby’s temperature to spike higher. Monitor their temperature closely and do not put the Merlin suit back on until the fever has passed.
With certain health conditions
There are some health situations where a doctor may advise against using a Merlin sleep suit or similar swaddle products:
- Hip dysplasia – Restricting leg movement with swaddles may worsen hip positioning issues
- Reflux – The Merlin suit puts pressure on the abdomen that may worsen reflux
- Overheating concerns – Babies prone to getting overheated cannot be properly temperature regulated in an insulated suit
- Allergies – The materials may cause skin irritation
- Elevated risk of SIDS – Doctors may restrict motion-restricting products for preemies or babies with apnea
If your baby has any underlying conditions, be sure to check with your pediatrician before trying a Merlin suit. They can help identify any special precautions needed.
If your baby stops liking it
It’s common for babies who have been happily sleeping in their Merlin suits for months to suddenly start resisting the suit. They may cry when put into the suit or repeatedly try to squirm out of it. Some babies decide they no longer like that enclosed feeling as they grow. Others may just be going through a typical period of fussiness with their sleep cycle.
If your formerly content Merlin baby is suddenly rejecting the suit upon hitting 4-6 months old, don’t force the issue. Listen to your baby’s cues and try transitioning to a regular wearable blanket or sleep sack instead. While some babies adapt to the Merlin suit again after a break, forcing an unhappy baby to wear one can lead to unsafe rolling attempts or overheating from frustration.
Conclusion
The Merlin sleep suit can be a wonderful product to help babies sleep more soundly during the newborn and infant months. However, there are important times when use of the Merlin suit should be halted. Stop using the suit as soon as baby shows roll-over capability, by 12 months old at the latest, or if baby seems unhappy or overheated. Do not layer additional swaddles with the Merlin suit. And remember that safety should always come before sleep when making decisions about sleep aids. If in doubt, check with your pediatrician on the best sleep options for your baby’s specific needs and milestones.