Based on what you've described, it seems you’re generally healthy and active — doing yoga and even climbing stairs without any issues is a good sign.
However, experiencing breathlessness at night after workouts (especially when lying down) could be due to:
Exercise-induced muscle fatigue
Postural issues or mild acid reflux that worsens when lying down
Poor ventilation during workouts
Occasionally, anxiety or shallow breathing patterns
Next Steps
Most of these are not serious, but to be safe, I recommend:
1. Avoid heavy meals and intense workouts too close to bedtime
2. Try sleeping slightly elevated with a pillow under your upper back
3. Focus on deep breathing (diaphragmatic breathing) post-workout
4. Ensure your workout space is well-ventilated
Health Tips
If symptoms persist, worsen, or are accompanied by chest tightness, palpitations, or dizziness, please consult a doctor for an ECG, chest exam, or lung function test to rule out hidden issues like mild asthma, GERD, or cardiac concerns.
Take care and feel free to follow up for further guidance.