When did parenting around sleep get so confusing?

One minute the midwife at the hospital is tightly wrapping your new baby, the next the internet is yelling at you to move to a sleep sack due to the risk of rolling!

You could swear you only just arrived home from the hospital a few weeks ago, is it really time to move on from the swaddle?

If you’re wondering whether it’s time to stop swaddling and start using a sleep sack (swaddles and sleeping bags for baby sleep), you’re not alone. When we host our Sunday sleep session, this question pops up, every week!

That transition can feel emotional (and a little scary), it’s a sign your baby is growing up, but it’s also an important safety and developmental step. Let’s talk about it gently and practically.

What is the difference between a swaddle and a sleep sack?

A swaddle is a snug wrap (a light blanket or specially designed swaddle) that secures your baby’s arms to reduce the startle (Moro) reflex and often helps newborns settle. Research shows swaddling can increase quiet sleep and reduce sleep-state changes in infants who are new to swaddling. [1]

A sleep sack (wearable blanket) slips on and keeps your baby warm without loose bedding while allowing arm and leg movement. Sleep sacks remove the risk of loose blankets and are the safer option once your baby begins rolling. [2] [3]

A sleep sack also keeps your baby warm in winter when they would otherwise kick off their covers, and is a positive sleep association all year round!

When should I stop swaddling—and start using a sleep sack?

The usual guidance is to stop swaddling when your baby shows any sign of rolling from baby to tummy. Many infants begin attempting to roll between roughly 2 and 4 months. Continuing to swaddle after rolling begins increases risk because a swaddled baby may not be able to push up or turn their head safely. [3] [5]

So how do you know if it’s time? Look for early rolling cues like a shoulder lifting, a twist in sleep, or accidental side-lying, and plan your transition then. That moment is both a safety cue and a developmental milestone worth honouring.

Over the last 13 years as baby sleep consultants, we have observed 80% of our clients begin to roll back to tummy around 5-6+ months, while 15% master this skill early between 4-6 months, and only 5% roll earlier that 4 months. (back to tummy, not tummy to back).

It’s not an easy skill to master.

What are the signs my baby is ready to transition?

Common signs I see with sleep-deprived parents:

• Your 8-week-old is lifting head and shoulders during sleep or nap time.
• Your 3-month-old pushes up on elbows during tummy time and ends up on their side in the swaddle.
• Baby clearly fights the wrap or the swaddle feels very tight (you can’t fit two fingers between chest and fabric).
• The startle reflex is gone or is very minor.
• Your baby shows signs of wanting to use their hands to soothe themselves during awake times, or when tired.

When you notice these, plan a gentle transition. You’re responding to growth, not failing at sleep.

Why does making the switch matter?

Switching at the right time matters for safety and healthy development:

• Safety: A swaddled infant who rolls faces higher risk of unintentional suffocation — so stop swaddling once rolling begins. [3]
• SIDS risk: Some reviews show swaddling can reduce arousability and may be associated with elevated risk when infants sleep prone or as they get older — which is why timing matters. [5]
• Hip health: Tight, leg-straightening swaddles can adversely affect hip development, hip-healthy swaddling keeps hips flexed and spread. [4]
• Development: Letting arms out supports hand-to-mouth discovery and self-soothing - important steps toward independent settling. [1]

How long can I safely swaddle before transitioning?

Swaddling is most helpful in the early newborn weeks (0–3 months) to calm a strong startle reflex. Many families continue into month 3 and early month 4 if rolling hasn’t started, but remain vigilant for mobility cues. Some experts advise stopping around ~3 months as a conservative approach. [3]

How can I help my baby with the transition from swaddle to sleep sack?

Gentle, practical steps that work for exhausted parents:

1. One arm free first: A gradual release (one arm, then both) is less stressful for many babies.
2. Pick the right sleep sack: Breathable fabric, correct sizing, hip-friendly design and appropriate TOG rating — avoid weighted sleep sacks. [7] [6]
3. Keep the bedtime routine the same: Same bath, book, dim lights — only the sleepwear changes, not the ritual.
4. Adjust layers, not weight: Use TOG guidance for room temperature and clothing layers rather than piling blankets. [6]
5. Offer reassurance: Extra pats, calm voice and a slightly longer wind-down may help the first few nights.

Most babies adapt within a week or two; some need more time. Be patient — short discomfort now for safer, more independent sleep later.

Can I ever go back to swaddling after starting a sleep sack?

If your baby has begun rolling, return to a tight swaddle is not advised because of safety concerns. If they haven’t started rolling and are under 4 months, you were just testing the sleep sack, and after 3 nights sleep is a disaster, you can return to the swaddle and try again in a week or 2. [3]

What comes next after the switch?

After your baby accepts the sleep sack you can:

• Choose season-appropriate TOG sacks (lightweight for summer, warmer TOG for winter). [6]
• Keep the same sack for naps to build consistency.

You’ve got this

Transitioning from swaddle to sleep sack mixes pride and grief, and that’s okay. You’re responding thoughtfully to your baby’s development and keeping sleep safer. If you’re unsure, check rolling and motor skill cues with your pediatrician. Small, gradual steps, consistent routines, and your calm presence will get you through. You’re doing an amazing job.

References

1. Dixley A. The effect of swaddling on infant sleep and arousal (systematic review). PMC. 2022.
2. Parents.com — Should I Use a Swaddle or Sleep Sack on My Baby?
3. HealthyChildren (American Academy of Pediatrics) — Swaddling: Is it Safe for Your Baby?
4. International Hip Dysplasia Institute — Hip-Healthy Swaddling.
5. Pease AS et al., Swaddling and the Risk of Sudden Infant Death Syndrome. (PubMed / Pediatrics abstract).
6. NHS Start for Life — Safe sleep advice and TOG guidance for baby sleep clothing.
7. Parents.com — Are weighted sleep sacks safe for babies?