The best TOG rating for your baby sleep sack depends on the room temperature. For Hushabye sleep sacks, a 0.5 TOG is ideal for warm rooms (24°C/75°F and above), while a 1.0 TOG is suitable for moderate temperatures (21°C/70°F). For cooler rooms (16-20°C/61-68°F), a 2.5 TOG will keep your baby warm and cozy. Always ensure your baby is not overheating by checking their neck or back. It's important to dress your baby appropriately underneath the sleep sack to maintain a comfortable and safe sleep environment.