Seasonal affective disorder SAD winter blues biology seasons circadian rhythm light therapy mood depression winter depression science research UK Biobank bipolar disorder sleep patterns natural light therapy tips Discover how scientists are uncovering the biological roots of seasonal affective disorder, or SAD. This video explores the link between changing seasons, our internal clocks, and mood swings, drawing from recent research like the UK Biobank studies. Learn why winter brings fatigue, sadness, and cravings for carbs, and how reduced daylight disrupts hormones and sleep. We'll cover differences between mild winter blues and clinical SAD, seasonal gene changes in the body, and effective treatments including bright light therapy, cognitive behavioral therapy, and natural sunlight exposure. Plus, expert insights from researchers on bipolar disorder and sleep data from millions. If you're feeling the winter slump, this guide offers science-backed ways to reclaim your energy and joy in the darker months. Stay tuned for practical tips to beat the winter blues naturally.