Getting 7 to 8 hours of sleep every night is widely considered essential for good health, but a new study suggests that sleep duration alone is not enough. Experts now warn that sleeping at irregular times—sometimes at 11 pm, sometimes at midnight—can significantly increase the risk of several serious illnesses.

In today’s fast-paced lifestyle, disrupted sleep schedules have become common. Heavy workloads, late-night screen time, and digital addiction often push people to sleep late. While going to bed an hour later occasionally may not seem harmful, experts say that consistently irregular sleep timing can have long-term health consequences.

A recent study published in the scientific journal Health Data Science tracked the sleep patterns of 88,461 people using wearable devices. The findings revealed that people who went to bed at different times each day or stayed up late at night had a higher risk of developing various diseases.

Explaining the impact of sleep irregularity, Dr. Bipin Kumar Sharma, consultant neurologist at Kailash Deepak Hospital, said another major study published in Nature Medicine used sleep data from over 65,000 individuals. Researchers trained an artificial intelligence model using polysomnography—an advanced sleep analysis technique—which can now predict the risk of more than 130 diseases. According to him, doctors increasingly stress not just sleep duration but also proper sleep hygiene and consistency.

Risk of Serious Health Problems

Experts say poor and irregular sleep is linked to conditions such as obesity, high blood pressure, heart disease, stroke, diabetes, dementia, and even heart attacks. Inadequate sleep also weakens the immune system, making the body more vulnerable to infections.

On average, adults require 7 to 9 hours of sleep each night, while children and teenagers need even more. However, quality sleep is equally important. Frequent awakenings or disturbed sleep reduce the body’s ability to recover and regenerate.

Biological Clock Gets Disrupted

Dr. Bharat Kumar Surisetti, consultant neurologist and spokesperson at Yashoda Hospitals, Hyderabad, explained that the human body runs on a biological clock known as the circadian rhythm. Irregular sleep timings disrupt this rhythm, leading to hormonal imbalances. Hormones such as cortisol, thyroid hormones, and growth hormone follow a fixed daily cycle, and disturbed sleep can interfere with their normal release.

Irregular sleep also affects hunger-regulating hormones like ghrelin and leptin, increasing cravings for junk food and excess calories. This can lead to weight gain, insulin resistance, and a higher risk of diabetes. Mental health issues such as anxiety, depression, irritability, and memory problems are also linked to poor sleep patterns.

How to Improve Sleep Routine

Experts recommend going to bed and waking up at the same time every day to maintain a healthy sleep cycle. Avoid caffeine in the evening, limit screen time before bed, and try light exercise or relaxation techniques. A warm bath before sleeping and reducing mobile phone usage can also help improve sleep quality.

Maintaining a consistent sleep schedule, experts say, is just as important as getting enough sleep—and ignoring it could quietly increase the risk of serious illness.