Comparing the Efficacy of Heated Yoga and Sauna as a Treatment for Depression

This study is comparing two heat-based treatments — heated yoga classes and sauna sessions — as non-drug approaches to treating depression. The goal is to see if regular sessions of either activity can meaningfully reduce depressive symptoms, based on the idea that raising core body temperature may have mood-lifting effects. **You may be eligible if...** - You are between 18 and 65 years old with moderate or greater depression (PHQ-9 score above 10) - You speak English and can travel to specific studio locations near Harvard Square, Massachusetts - You are physically able to participate (no serious unstable medical conditions) - If you take psychiatric medications, your dosage must have been stable for at least 4 weeks **You may NOT be eligible if...** - You are pregnant or breastfeeding - You have active suicidal thinking - You have bipolar disorder, psychosis, active eating disorder, or active substance use disorder - You have had a bone fracture or joint surgery in the past 6 months - You have significant prior exposure to heated yoga or sauna in the past 3 months - You are taking medications that increase dehydration risk (such as lithium, diuretics, or insulin) Talk to your doctor to see if this trial is right for you.