Developed and developing countries around the world are seeing a significant increase in obesity rates and type two diabetes.
In the UK, the NHS estimates that one in four adults are clinically obese and one in five children aged 10 to 11, with many more being overweight.
Professor Ahmad Agil, who led the study, said the epidemic is primarily caused by humans' failure to adapt to modern environments, sedentary lifestyles, higher consumption of high-calorie processed food and excessive exposure to artificial lightning reducing melatonin levels.
He described the hormone, which is naturally present in plants, animals and humans, as a "hormonal signal released during the night to establish circadian rhythms".
Scientists say artificial light disrupts the body's hormone production during sleep. Photo / Thinkstock
Professor Agil said: "Currently this process is frequently interrupted, as a result of excessive exposure to artificial lightning during the night, which reduces the levels of endogenous melatonin. "For instance, many people are in the habit of sleeping with their lamps, televisions or their computers switched on, or with the blinds drawn up.
"For all these reasons, it is important to try to sleep in absolute darkness, to avoid interference in the generation of melatonin."
The hormone is found in particularly high quantities in spices, herbs, tea, coffee, fruit, nuts and seeds.
- Independent
