**This study focuses on sleep and brain function in kids with sickle cell disease (SCD).** Sickle cell disease is a blood disorder where red blood cells can form a sickle shape and cause health problems. The study is for kids aged 12-18 with any type of SCD. The research will look at sleep issues using a special remote test called peripheral arterial tonometry (PAT) and some questionnaires about sleep. The PAT test will be done at home using devices called WatchPAT and Circul+ Ring, which are worn overnight for three nights. The study will also check brain functions like memory and behavior during a regular clinic visit. **Key Points:** - The study lasts a few weeks, with home and clinic visits. - Participants will use provided devices at home and complete questionnaires. - No compensation is mentioned; risks are minimal, mostly related to device use. Eligible participants must have SCD, be 12-18 years old, speak English, and have a smartphone or tablet. Those with certain health issues or undergoing specific treatments cannot join. Participants and their guardians must agree to the study rules.