Efficacy and safety of stellate ganglion block with different volumes of ropivacaine to improve sleep quality in patients with insomnia: a comparative study.

4 mL of 0.375% ropivacaine for ultrasound-guided SGB is sufficient to improve the sleep quality of insomnia patients, whose overall risk is lower than block with 6 mL or 8 mL of ropivacaine.