There are two parts to this study. First, we want to determine the reliability of a wearable device for sleep quality in RTT against the gold-standard polysomnography. Additionally, we want to determine whether sleep quality measured by the E4 device serves as a valid construct for sleep measurement and is clinically meaningful when compared to existing clinical instruments in RTT. These assessments will allow for direct comparison of the sleep assessments using the gold standard PSG to those acquired using the E4.

Participation in this study takes 7 consecutive days. First, participants will receive an in-person clinical evaluation with a child neurologist (either Dr. Cary Fu or Dr. Jeff Neul) using the Motor Behavior Assessment. At this clinical visit, your child will be fitted with an E4 device. Your child will wear the E4 biosensor watch home and for the next 6 days at home. The biosensor will monitor and record physiological signals in real time. It will also measure Blood Volume Pulse, sympathetic nervous system arousal, local skin temperature, as well as hand movements.

Families can choose to participate in a second optional component of this study by participating in an overnight polysomnography (PSG) at the Vanderbilt University Medical Center鈥檚 sleep lab, while the child is wearing the E4 watch. We will conduct a standard PSG protocol with monitoring of respiratory effort, nasal airflow, blood oxygen saturation, heart rate, electrooculography (EOG), surface electromyography (EMG), and EEG.  

Caregivers will be asked to keep a daily sleep diary and complete the Child Sleep Habits Questionnaire (CSHQ), the Rett Syndrome Behavior Questionnaire (RSBQ), and the Child Health Questionnaire (CHQ).  Caregivers will also complete the SF-36 Questionnaire which is a 36-item parent quality of life survey, which is designed to assess eight health concepts: physical functioning, bodily pain, role limitations due to physical health problems, role limitations due to personal or emotional problems, emotional well-being, social functioning, energy/fatigue, and general health perceptions. A subset of 22 participants will wear the E4 device during the 7th night while concurrently undergoing a conventional polysomnogram at Vanderbilt University Medical Center.