‘I stay up all night and sleep in the day; been doing it for a while now. My life is built around it. Will this affect my health in the future?’

“Yes, consistently reversing the sleep cycle can affect overall health,” he explains. The body’s circadian rhythm is designed around daylight. Long-term disruption can weaken immunity, affect lung function, slow metabolism, and raise the risk of hypertension, diabetes, and heart disease.

How a reversed sleep cycle stresses the body

The impact is not limited to physical health. “Night wakefulness disrupts hormones like melatonin and cortisol, which regulate sleep, stress and energy,” Dr Kumar says. When these hormones fall out of sync, people may experience irritability, low mood, poor concentration, persistent fatigue, and even changes in appetite or weight.

Many assume the body will simply adapt. While some adjustment occurs — particularly in long-term night workers — it is never complete. “The body can partially adapt… but it never fully resets,” he notes. Daytime sleep tends to be lighter and shorter due to light exposure and environmental noise, leaving the body to function under subtle physiological stress.

Warning signs often appear gradually: constant tiredness despite enough hours in bed, frequent respiratory infections, headaches, mood swings, breathlessness, or increasing reliance on caffeine.

Reducing risks if night schedules are unavoidable

For those who must live on a night schedule, protective habits matter. Maintaining a consistent routine is crucial. Dr Kumar advises using blackout curtains, minimising noise, avoiding heavy meals before sleep, limiting caffeine late in the shift, and ensuring 7–8 hours of uninterrupted rest.

Regular exercise supports metabolism and mood, while periodic health check-ups help detect early strain. These steps don’t completely erase the stress of circadian disruption, but they significantly reduce long-term health risks.

The key message is awareness. Human biology evolved around daylight rhythms, and regularly overriding that system has consequences — often subtle at first, but meaningful over time. With structure and proactive care, night-schedule living can be made safer for both physical and mental health.

DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.