Parkinson's disease (PD) is a brain condition that causes problems with movement, like shaking (tremor). Usual treatments like medication might not always work well. A new way to help is called *transcranial alternating current stimulation* (tACS), which uses gentle electrical currents on the head to reduce shaking. This study will try a special kind of tACS that works in sync with the natural tremor signals in the body to see if it helps reduce shaking in people with PD. The study will have two sessions using a safe level of tACS (2-4 mA) and will check how well it works.

• Participants will attend two study sessions.
• Only adults with moderate to severe hand tremor from PD can join.
• Major health issues or pregnancy exclude participation.