For years, doctors have warned that sleeping too much can raise the risk of heart disease, depression, and even early death. But a new study suggests the real problem may not be the number of hours we sleep, it’s how irregular our sleep patterns are. In today’s fast-paced world, many of us prioritise work, screens, or late-night tasks, and these habits often stay on our minds even as we try to sleep, leading to disrupted rest. But did you know such irregular sleep patterns may increase the risk of more than 170 serious diseases? Yes, you read that right. The study found that many people who claimed they slept more than eight hours were actually getting only six hours or less.
Most people misjudge how long they sleep
The research, published on June 3, 2025, in the journal Health Data Science, tracked the sleep of nearly 90,000 adults using fitness trackers. Participants were then followed for seven years to see how their sleep affected their health.
These “false long sleepers” may have distorted results from earlier research that relied only on self-reported sleep.
“When we looked only at people who both reported and actually had long sleep, the health risks linked to long sleep almost disappeared,” said lead researcher Dr. Qing Chen from China’s Third Military Medical University.
Poor sleep rhythms linked to many diseases
Instead of long sleep, the study found that irregular sleep patterns were the real danger. People whose sleep was disrupted, inconsistent, or fragmented were more likely to develop serious health conditions.
The analysis linked disrupted sleep to 172 different diseases. Those with the most irregular sleep had up to three times the risk of age-related frailty and double the risk of developing gangrene.
Some of the strongest links were:
- 37 per cent higher risk of Parkinson’s disease
- 36 per cent higher risk of Type 2 diabetes
- 22 per cent higher risk of acute kidney failure
Researchers estimated that for 92 conditions, more than 20 per cent of cases could potentially be avoided with healthier sleep habits.
Sleep consistency matters more than hours
While most health guidelines recommend 7–9 hours of sleep each night, this study shows that the timing and regularity of sleep may be even more important.
The findings also connected irregular sleep to 83 conditions that had not been linked to sleep before, including COPD, kidney failure, and diabetes. The results were further confirmed using US data, making the evidence stronger.
Researchers also found signs that poor sleep may harm the body through chronic inflammation. Blood tests showed higher levels of white blood cells and C-reactive protein in people with irregular sleep.
The study had some limits. It included mostly healthy adults from the West and measured only a week of sleep data. But experts say the message is clear: a consistent sleep routine could protect you from dozens of serious diseases.