3 min readNew DelhiMar 1, 2026 06:00 PM IST Staying up all night may feel manageable — until your body starts pushing back. A reversed sleep cycle doesn’t just cause tired mornings; over time, it strains the body’s internal clock, affecting immunity, hormones, and even breathing. According to pulmonologist Dr Sudhir Gupta (Chest Physician), Kailash Hospital, Noida, these effects build gradually, and many people ignore the early warning signs. Speaking from clinical experience, he says the body rarely stays silent when its rhythm is disturbed — it signals distress in ways that are easy to dismiss as stress or burnout. Fatigue that never really lifts One of the earliest red flags is exhaustion that doesn’t improve even after a full sleep window. This reversed rhythm “desynchronizes” the brain’s master clock. “Melatonin production gets suppressed by daytime light exposure (even through curtains), leading to poor sleep depth,” says Dr Gupta. Daytime sleep tends to be lighter and more fragmented, preventing proper recovery. This shows up as brain fog, irritability — “that feels like constant PMS or …