Doing night shifts can become reason for death: 3 reason why biology says your body is not built for it

Working late into the night may seem like a normal part of modern life, but growing scientific evidence suggests that it could be taking a serious toll on health. Doctors, nurses, factory workers, call centre employees, and security staff often keep the world running while others sleep — yet their bodies may be paying the price. Recent research has found that staying awake through the night and sleeping during the day goes against the body’s natural design, leading to long-term harm that includes increased risk of heart disease, irregular heart rhythms, and even premature death.

1. Disrupted circadian rhythm strains the heart
The human body follows a 24-hour internal clock known as the circadian rhythm, which regulates sleep, metabolism, hormones, and temperature. When a person works at night and rests during the day, this rhythm becomes misaligned with natural light and dark cycles. Scientists have found that this disruption affects multiple body systems simultaneously.

At night, the body’s metabolism naturally slows down, yet night shift workers often eat during these hours. This mismatch causes spikes in blood sugar and fat levels, which can lead to insulin resistance and elevated cholesterol over time. The heart then has to work harder, raising the risk of long-term cardiovascular disease.

In addition, shift workers often struggle to achieve deep, uninterrupted sleep during the day. This lack of rest keeps stress hormones such as cortisol elevated, which increases blood pressure and heart rate. Over time, this constant strain can trigger inflammation and damage blood vessels, further burdening the heart.


2. Chronic inflammation and cholesterol imbalance
A large-scale review published in Environmental Research analysed over 8,000 studies on night shift work and cardiovascular health, with 81 meeting the highest research standards. The review revealed that night workers showed higher levels of inflammation markers such as C-reactive protein and white blood cells — both indicators of chronic stress on the body.

Long-term inflammation can damage arteries and contribute to plaque buildup. Researchers also found that night shift workers had lower levels of “good” HDL cholesterol, which helps clear “bad” LDL cholesterol from the bloodstream. Reduced HDL levels can make arteries more prone to blockage, raising the risk of heart attack or stroke.

The review further noted that the risk rises with the frequency and duration of night shifts. Those who worked irregular hours for over a decade faced the greatest danger of developing cardiovascular complications.

3. Irregular heart rhythms and cardiac strain
Beyond metabolic changes, studies have shown that night shifts can directly affect heart rhythm. Researchers observed that night workers often experience prolongation of the QT interval — a measure on an electrocardiogram (ECG) that tracks how long the heart takes to reset between beats. A longer QT interval increases the likelihood of arrhythmias, or irregular heartbeats, which can be fatal if untreated.

Older individuals and long-term shift workers were especially vulnerable. One major population study found that those on rotating night schedules faced a significantly higher risk of atrial fibrillation, a condition that causes the heart to beat abnormally fast or irregularly.