In the UK and US, the practice of carrying an infant in a sling, wrap, or soft baby carrier is known as 'baby wearing'. It's less common for parents in the UK to use a sling for their infants' daytime sleep but there are many reasons why this may be helpful.
Why might slings be helpful for daytime sleep?
Around the world infants are carried by their mothers (and fathers, siblings and community members) throughout the day. These infants spend their days sleeping in a sling, which is usually made from a simple piece of cloth. Carrying infants in this way facilitates breastfeeding and maintains the close mother-infant proximity that they - as far as our evolved biology is concerned - expect (Lozoff & Brittenham 1979; see also How Babies Sleep).
As with many (even most) other child-care practices and products, very little research has been done to enable us to assess the potential benefits or risks of using slings for periods of day-time sleep. It may be possible, however, to make inferences based on research done in related fields.
Research (e.g. Morgan et al., 2011; Anisfeld et al., 1990) investigating the impact of close contact (usually skin-to-skin contact, but also contact associated with carrying) in neonates has shown that close contact increases infant sleep duration and the proportion of quiet sleep. Mothers can identify feeding cues more easily and quickly (Furman et al., 2002) and breast milk production is improved (Hake-Brooks & Anderson, 2008). Some research shows that mothers who hold their infants feel calmer, and less anxious, and show less cortisol reaction to stress (Heinrichs et al., 2001). One study (St James-Roberts et al., 2006) which examined infant crying and feeding in relation to the amount of time spent being carried (and also considered frequent breastfeeding, quick response to crying and bed-sharing) found that more carrying (and bed-sharing) was associated with less crying overall, but more frequent waking and more crying at night at 12 weeks.
Slings and SIDS
Using slings for daytime sleep may help parents who want their hands free while providing their infant with the close contact he or she needs - and at the same time avoiding one of the key day-time SIDS risks; leaving an infant alone during sleep (Blair et al., 2006). While some highly publicised infant deaths have occurred recently in babies being carried in a sling, these appear to have occurred predominately in ‘bag style’ slings, in which the infant reclines curled up, with their chin pressed down toward the chest. Guidelines are available to help parents choose and fit slings. See www.schoolofbabywearing.com/Images/TICKS.pdf and Which? for more information.