BDNF and depressive disorder: This study specifically aimed (a) to assess the impact of this 4-day guided, experiential meditation retreat on mental health and well-being (happiness, awareness, well-being, anxiety, and depression), (b) to correlate reported psychological changes with objective blood biomarkers (eCBs and BDNF) immediately after the retreat, and (c) to assess any persistent impact on participants' psychological well-being one month after the retreat.