Over the years there have been numerous innovations and fads that purport to help babies sleep. Some of these, like Houdini-proof swaddles and basic cotton sleep sacks, have become nursery staples that actually do improve sleep. On the other hand, other devices have fallen out of fashion due to limited benefits or have been recalled over significant safety concerns. The latest trend in baby sleep attire is weighted sleep sacks, but do they live up to the hype?
Weighted blankets first emerged as a tool to help caregivers calm children with sensory processing disorders. The majority of scientific literature supporting the use of weighted blankets comes from studies of school-aged children with autism spectrum disorder and attention deficit hyperactivity disorder. In these populations, studies are mixed about whether they actually improve sleep outcomes. A few studies found that children with autism experienced improved sleep maintenance and a faster time to fall asleep. However, the studies showing positive benefits often only included a few children, while more rigorous studies have typically not found any benefits to sleep. A recent systematic review, which is a methodological approach to reach a conclusion based on compiling the results of many studies, found that there is some evidence to support that weighted blankets reduce anxiety, but "not enough evidence" that they improve sleep (Eron et al. 2020). However, several studies have shown that despite no observable positive benefits, children and parents like using weighted blankets.
There are currently no peer-reviewed studies examining the use of weighted blankets or sleep sacks in medically typical infants or toddlers. One recent study using weighted blankets for NICU newborns with Neonatal Abstinence Syndrome (i.e., babies born with withdrawal symptoms due to maternal opioid use) found that covering an infant with a weighted blanket for 30 minutes at a time reduced the baby's heart rate and symptoms of withdrawal (Summe et al. 2020). That study also found that the babies did not experience a significant increase in body temperature or change in respiratory rate while wearing the weighted blanket. However, that study did not assess sleep outcomes.
The main takeaway from the scientific literature is that there is no evidence one way or another to support the use of weighted sleep sacks during sleep for medically typical children.
Believe it or not, companies do not have to go through any sort of official safety certification to sell infant sleep attire (sleep surfaces, such as cribs and bassinets do have specific CPSC safety requirements that you can read here). You might assume that because something is for sale it is safe, but the reality is that business is often ahead of science. We just don't know whether weighted sleep sacks pose safety risks beyond typical sleep sacks. The limited research that has been done doesn't suggest there are significant safety hazards; however, infants were monitored while wearing weighted blankets in the studies that do exist. If you decide to purchase one, consider the following:
Use as directed.
If your baby does not meet the age or size requirements for a weighted sleep sack, then don't use it. Never use a loose blanket, weighted or otherwise, for a baby under 12 months old.
Weighted sleep sacks are heavier than cotton sleep sacks. Overheating is a serious safety concern for babies, so if you use a weighted sleep sack, then dress your baby in lighter pajamas than you would with a typical sleep sack. You might even want to lower the temperature in your baby's room a degree or two. Monitor your baby by putting two fingers on your baby's chest while wearing the sleep sack. If s/he feels hot to the touch, then you should dress your baby in lighter fabrics, lower the room temperature, or discontinue using the weighted sleep sack.
Entanglement and rolling.
We haven't seen any reports of babies becoming entangled or stuck on their bellies in weighted sleep sacks, but if your baby is strong or the Houdini type who can break out of swaddles, then you should monitor your baby to ensure that s/he doesn't get an arm caught inside the sleep sack. At this point, we would only recommend using weighted sleep sacks for naps when you can supervise your baby. This won't guarantee that it is safe, but it will give you a sense of how your baby moves and sleeps in the sleep sack. If your baby gets stuck in any way, then stop using the weighted sleep sack.
Although the NICU study didn't find any changes in respiration, the babies in that study only wore the weighted blankets for a short duration of time and they were always supervised. They also did not wear the weighted blanket during sleep. Respiration changes during sleep and there are no studies that have examined infants' breathing patterns during sleep while wearing a weighted sleep sack. If you observe your baby experiencing any labored breathing, then stop using the weighted sleep sack.
Check with your pediatrician.
It's always a good idea to ask your pediatrician if a weighted sleep sack or blanket would be appropriate for your child.
The Bottom Line: Should you buy a weighted sleep sack or blanket for your baby or toddler?
Although there is not strong scientific evidence to suggest that there are benefits to using a weighted sleep sack, there really hasn't been enough research into this topic. Babies and toddlers with known sensory processing issues may experience reduced anxiety while using a weighted sleep sack for brief, supervised periods of time during the day. Anecdotally, many parents report that their babies sleep better than with a normal sleep sack. Just as with adults, babies differ in their preferences for sleep attire. You may find that your baby likes the sensation of gentle pressure during sleep. Remember though, many sleep problems stem from sleep associations (i.e., the way your baby has learned to fall asleep), which means that if your baby is accustomed to being rocked or fed to sleep, a weighted sleep sack will probably make no difference at all (if you suspect this is the case for your baby, then check out our online sleep class).
The bottom line is that weighted sleep sacks are not the solution to all sleep problems. You may find that your baby sleeps better in a weighted sleep sack or it may make no difference at all. Given the lack of information on safety, we would recommend that you avoid using weighted sleep sacks and blankets for sleep. If you do decide to try one, we recommend only using it for short periods of time while you can supervise your baby, such as during a nap.
Summe, V., Baker, R.B., Eichel, M.M. and Cleveland, L., 2020. Safety, Feasibility, and Effectiveness of Weighted Blankets in the Care of Infants With Neonatal Abstinence Syndrome: A Crossover Randomized Controlled Trial. Advances in Neonatal Care, 20(5), pp.384-391.
Eron, K., Kohnert, L., Watters, A., Logan, C., Weisner-Rose, M. and Mehler, P.S., 2020. Weighted blanket use: a systematic review. American Journal of Occupational Therapy, 74(2), pp.7402205010p1-7402205010p14.
Gringras, P., Green, D., Wright, B., Rush, C., Sparrowhawk, M., Pratt, K., Allgar, V., Hooke, N., Moore, D., Zaiwalla, Z. and Wiggs, L., 2014. Weighted blankets and sleep in autistic children—A randomized controlled trial. Pediatrics, 134(2), pp.298-306.
France, K.G., McLay, L.K., Hunter, J.E. and France, M.L., 2018. Empirical research evaluating the effects of non-traditional approaches to enhancing sleep in typical and clinical children and young people. Sleep medicine reviews, 39, pp.69-81.
Bolic Baric, V., Skuthälla, S., Pettersson, M., Gustafsson, P.A. and Kjellberg, A., 2021. The effectiveness of weighted blankets on sleep and everyday activities–A retrospective follow-up study of children and adults with attention deficit hyperactivity disorder and/or autism spectrum disorder. Scandinavian Journal of Occupational Therapy, pp.1-11.
Gee, B.M., Peterson, T.G., Buck, A. and Lloyd, K., 2016. Improving sleep quality using weighted blankets among young children with an autism spectrum disorder. International Journal of Therapy and Rehabilitation, 23(4), pp.173-181.
Gee, B., McOmber, T., Sutton, J. and Lloyd, K., 2017. Efficacy of weighted blankets for children with autism spectrum disorder, sensory overresponsivity, and sleep disturbance. American Journal of Occupational Therapy, 71(4_Supplement_1), pp.7111515242p1-7111515242p1.