Baby sleeping bags are becoming very popular with parents, and are promoted as a way of reducing the risk of SIDS
The main justification is that baby sleep bags are intended to prevent babies from getting their heads covered with bedding during sleep. For this reason it is important to ensure babies are not placed in sleeping bags that are too big, and that they could slide down in to. Many parents feel they help babies sleep better, by preventing them from wriggling out of bedding or kicking off blankets, and keeping them at a comfortable temperature.
In the UK and elsewhere, studies have shown that overheating increases the risk of SIDS compared to babies sleeping at cooler temperatures. It is claimed that the use of baby sleep bags could help avoid overheating, but very little research has examined whether they actually do keep babies’ temperature at a safe level, or reduce the risk of SIDS. One fairly old study suggested sleeping bag use was associated with lower SIDS risk. One recent, but very small study (eleven babies) showed that babies using sleep bags had lower body temperature and less change in body temperature during a day time nap. This may suggest that sleep bags can help prevent overheating; however babies’ temperature profiles differ during day-time, compared to night-time, sleep. A more recent paper by the same team reported that there was no difference in body temperature of 15 babies after sleeping under blankets for 60 minutes, vs in a sleeping bag for 60 minutes. Although sleep bags may be useful they may also keep them sleeping on their backs for longer, delaying babies in learning to roll onto their tummies.
Additionally no research has been done to look at how baby sleeping bags are actually used, and whether parents use blankets in addition to sleep bags. The UK’s biggest SIDS research and advisory body, the Lullaby Trust, recommends the use of baby sleep bags, however they also state that further research is needed to identify whether the proposed benefits of sleep bag use are real.