When it comes to choosing the best mattress for your child's bunk bed, there are a few key points to keep in mind. You'll want to make sure that the mattress is made from organic materials, firm enough to provide support, and the right size for the bunk bed. 
Materials:
To ensure your child is not exposed to any harmful chemicals or toxins while sleeping make sure that the mattress is made from organic materials. Check that the mattress and factory where the mattress is made are GOTS and GOLS certified. An organic mattress will provide a healthy night’s sleep and because it is made from sustainable materials, you can feel good about supporting a company that cares about the environment and is committed to eco-friendly practices. Size:
No matter what type of bunk bed you select, the best way to ensure your child is sleeping comfortably is to choose a mattress that is the correct size for your bunk bed. Bunk beds are sold in a variety of sizes and are typically compatible with twin mattresses or a combination of twin and full mattress sizes.Profile:
Low-profile mattresses are recommended for top bunks. These mattresses have a thickness of 8 inches or less. This lower profile ensures the mattress is thick enough to support the sleeper, but not too tall for the bunk and its safety rails. According to the U.S. Consumer Product Safety Commission, the mattress should be at least 5 inches shorter than the top of the rails. A hybrid mattress is one that is made with a combination of foam over innersprings. An organic hybrid mattress is commonly made with GOLS certified organic latex over an innerspring system. Some organic hybrid mattresses are made with cotton or wool comfort layers over an innerspring system. My Green Mattress perfected the hybrid bunk bed mattress by tweaking their innerspring system so that the mattress does not compromise support or comfort, while meeting the safety requirements of most bunk beds.