Get outside within 20 minutes of waking
Natural light hitting your retina is the single strongest signal your circadian system receives. It tells the suprachiasmatic nucleus, the brain's master clock, to anchor the cortisol awakening response (CAR) at the right time of day. A 2014 study published in the Journal of Biological Rhythms found that morning light exposure significantly sharpened the CAR peak and shortened its tail, meaning cortisol rose fast and fell cleanly instead of dragging through the afternoon. In most Indian cities, stepping onto a balcony or terrace for 10 to 15 minutes between 6 and 8 AM gives enough lux exposure to do this. Overcast days still work. Sunlight through glass does not, the UV filtering cuts the signal your retinas need.
