Why use knee sleeves?
Knee sleeves provide warmth and compression. They are great for mild aches and pains, even the early onset of osteoarthrtitis can be treated well with a knee sleeve.
A neoprene sleeve will improve circulation to the knee joint, and studies have shown a neoprene knee brace will also improve proprioception.
A knee sleeve is an inexpensive treatment option for mild knee problems. It is a good idea to try wearing one before spending money on a more significant knee orthotic. Wearing a neoprene knee sleeve will give you a good idea what wearing something substantial will feel like.
What about rashes? Most people that experience skin problems when wearing a neoprene brace don't realize that the knee braces need to be cleaned daily. How many days in a row would you wear the same pair of socks? Wash your knee sleeve in the sink with mild detergent after you wear it. Then let it air dry over night.