Night owls are more likely to develop type 2 diabetes.
Scientists have concluded that those who stay up late are at greater risk of the condition as their body clocks are out of sync with the rest of society.
Experts in the Netherlands analysed over 5,000 people in terms of sleep timing, waist circumference and body mass index (BMI) and found that those who stayed up less had a 46 per cent increased risk of type 2 diabetes than people who head to bed at more civilised times.
Dr. Jeroen van der Velde, lead researcher at Leiden University Medical Centre, said: "Previous studies have indicated that a late chronotype - preferring to go to bed late and wake up later - is associated with an unhealthy lifestyle.
"Late chronotypes are more likely to smoke or have an unhealthy diet, for example, and it has been suggested this is why they are at a higher risk of obesity and metabolic disorders including type 2 diabetes."