People who have sleep disorders and those who often work overnight are known to be at increased risk for type 2 diabetes.
Now, a new study conducted by researchers in Sweden sheds light on the link between melatonin and the disease, which could explain why type 2 diabetes tends to be more prevalent in people who lack sleep at night.
Melatonin plays a key role in regulating circadian rhythm. The amount of this naturally occurring hormone is influenced by light.
When it is dark, melatonin level increases which is why it peaks at night earning it the moniker “hormone of darkness.” It is also for this reason that it is used as a drug for sleeping. Source