Transcutaneous Auricular Vagus Nerve Stimulation for Insomnia in Survivors of Childhood Acute Lymphoblastic Leukemia

This pilot study will assess the usefulness and potential effectiveness of using transcutaneous auricular vagus nerve stimulation (tVNS) for treating insomnia in adult survivors of childhood acute lymphoblastic leukemia (ALL). Participants will be randomized to receive either active (verum) or inactive (sham) nightly stimulation using a non-invasive earbud device over two time periods: 2 weeks and 8 weeks. The study will assess adherence to the intervention and estimate its effects on sleep quality, stress, and neurocognitive function. Primary Objective: Aim 1: To determine a) short-term and b) long-term feasibility of tVNS in terms of participation in ALL Survivors with moderate to severe insomnia. Aim 2: To estimate the effect size of tVNS on sleep quality, stress, and neurocognitive outcomes in ALL survivors with insomnia. Exploratory Objectives Aim 1: To investigate the onset of tVNS effect via actigraphy measures over the intervention epoch. Aim 2: To estimate the effect size of genetic variants on sleep quality within verum tVNS.