Why don't Grobag Baby Sleep Bags have sleeves?

We at Grobag believe that Baby Sleep Bags should be sleeveless to aid heat loss and air circulation. (Babies sleeping under traditional blankets rarely sleep with their arms inside). The new British Standard also stipulates that Baby Sleep Bags should be “without sleeves or hoods”. In cooler weather, we recommend long-sleeve bodysuits, in addition to a long-sleeved pyjama top, pyjamas or a sleepsuit.