Should infants and adults sleep in the same bed together?

Over the past two decades, great advances have been made in identification of hazardous sleeping environments for infants and young children, with significant reductions in numbers of deaths.1 However, one issue that continues to incite heated debate is whether adult caregivers should sleep on the same surface as infants,2 referred to as “shared sleeping”.

It is recognised that infants who sleep in the same room as their carers have a reduced risk of sudden infant death syndrome (SIDS),3 possibly due to an increased level of direct supervision.4 However, what of infants who sleep in the same bed as their parents or carers?

First, it is important to clarify terminology. Although it is claimed that shared sleeping increases the risk of SIDS, it is perhaps more accurate to state that it is associated with an increased risk of infant death generally. An indication that shared-sleeping deaths may be different to “classical” SIDS deaths that occur among infants sleeping on their own is a finding of an almost equal sex ratio in shared-sleeping deaths, compared with the 2 : 1 male–female ratio among infants who died of SIDS.5 If some of the risk factors for shared-sleeping death (eg, parental obesity, fatigue, soft sleeping surfaces) are examined in isolation, accidental suffocation appears to be a more likely mechanism of death than subtle processes leading to SIDS.5 These apply to any shared-sleeping surface, not just to beds.

It is difficult to formulate absolute recommendations on shared sleeping, as the current incidence in most communities is unknown, and the form that it takes varies greatly between families. There are also cultural issues to take into consideration — for example, shared sleeping is very common in South-East Asian communities, but with low incidences of unexpected infant deaths.6

However, a study from Avon, United Kingdom, found a disturbing percentage increase in shared-sleeping deaths among two cohorts of infants who died of “SIDS”, from 12% (17/147 in 1984–1988) to 50% (18/36 in 1999–2003) (P < 0.001).7 The authors noted that although the number of shared-sleeping deaths that were not on sofas dropped (from 16 to 14), the decrease was not as great as that among infants who were sleeping on their own, perhaps explaining the increased proportion of unexplained infant deaths found in shared-sleeping situations. This difference may be due to mechanisms of death being different in the two circumstances. A similar effect was noted in South Australia, where the proportion of shared-sleeping deaths increased from 7.5% of “SIDS” deaths (23/306 in 1983–1990) to 32.3% (21/65 in 1991–1993).8 The percentage of deaths in shared-sleeping situations in the early part of the study also showed an overrepresentation compared with the shared-sleeping rate of 1.5% in the general community in 1988.8

As some infants are particularly vulnerable to the effects of airway occlusion,9 and as there is often no clinical predictor of this vulnerability, all that can be stated is that certain infants may be inherently at increased risk in a shared-sleeping situation. It is generally agreed that in Western cultures, the safest place for an infant is in a cot that meets recommended safety features and is positioned beside the caregiver’s bed.1,2

Supporters of shared sleeping cite advantages that include an increased incidence and longer duration of breastfeeding, enhanced maternal–infant bonding and improved settling.1 However, it has been reported that 50% or more of infants who are found unexpectedly dead are sleeping with an adult.10 The suggestion of possible accidental asphyxia by a parent “overlaying” a shared-sleeping child has been criticised, because it has been assumed that a parent would always arouse. However, parents can fail to wake if they are sedated or overly fatigued. There is an increased risk of infant death when caregivers have taken illicit drugs, smoked, or consumed more than two units of alcohol.10 In addition, it is not necessary for an adult to be lying over an infant completely for respiration to be compromised, as an infant who has rolled into a trough between a parent’s much larger body and a soft mattress may also be at risk.11 This is exemplified by the dangers of shared sleeping on a sofa.7

On occasion, parents state that they successfully slept in the same bed as all of their children without any deaths occurring. While such anecdotes are undoubtedly true, few risks are absolute and so it cannot be used as definitive evidence that shared sleeping is always a safe practice.

The key to assisting with this issue lies in adequately informing caregivers of potential risks. Clinicians should discuss with caregivers the risk factors for accidental asphyxiation in shared-sleeping arrangements, such as sedation, excessive fatigue and hazards predisposing to suffocation. This may help prevent infant deaths in the future.