Hello!Thank you for contacting Spa Sciences! What you are feeling is normal. This is the EMS technology. EMS is electronic muscle stimulation which is what helps to keep the muscles toned and skin-taught. You may feel the EMS more if the face is wet or damp or while using the face masks. EMS is optional. Used on all light modes except purple. You may also press the plus & minus buttons on the device to change the intensity of the unit. You may use your NURI device as needed and the LED lights as frequently as you would like. We recommend 1-3 minutes per area. • Red (anti-aging) • Blue (acne) • Green (brightness) • Purple (repairing damaged skin). We have provided the NURI user manual here:https://cdn.shopify.com/s/files/1/0067/4217/9913/files/NURI_Quick_Start_Guide_REVISED.pdf?v=1639655102. Please make sure to register your device on our website for the warranty here (https://spasciences.com/pages/device-registration). Please let us know if we can be further of assistance. Have a great day!