• Seasonal Affective Disorder (SAD): A type of depression tied to lack of natural sunlight. People with SAD often feel significantly better when they spend time outdoors or use light therapy that mimics sunlight.

• Vitamin D Deficiency: While not a psychological illness, lack of sunlight can cause fatigue, bone pain, and depression-like symptoms. Getting outside helps the body produce vitamin D naturally.

• Nature Deficit Disorder: Not a recognized medical diagnosis, but it describes the psychological and behavioral issues linked to spending too much time indoors — anxiety, restlessness, and lack of focus being common effects.

• Agitated depression or cabin fever: Some people with anxiety, PTSD, or mood disorders can feel suffocated or trapped indoors, and being outside brings physiological relief — lower cortisol, slower heart rate, and a return to a calmer baseline.

Go outside