Call it the result of increase in the level of melatonin, a hormone regulating the sleep-wake cycle in human beings, during winter or effective policing, criminals are lying low these bone-chilling days in the city.

Apart from the December 15 murder of a woman and her two daughters at their Indrapuri residence, November, December and January (till now) have not witnessed any major crime or any case of petty theft or snatching.

“Winter is a challenging season for the police, as the criminals tend to take advantage of the foggy mornings and nights. Besides, the extreme cold can be a deterrent for the police personnel on patrol duty and can reduce their alertness. Those on duty have been asked to be extra vigilant. For this, they have to follow a proper diet and morning exercise is a must,” a senior police officer told The Telegraph.

“We are also trying various forms of patrolling, particularly in the lanes and by-lanes of the residential areas. Keeping the dense fog cover in mind, we have intensified the decoy system of patrolling. The men in uniform patrol the residential areas on foot during night and early morning hours. Scattered all over, they move in plain clothes so that the criminals cannot identify them easily. The decoy system of patrolling is an effective way to check crime at this time of the year,” the officer added.

Residents staying indoors is another reason cited by the police for the decrease in criminal activities.

“There has been a drastic fall in the number of morning walkers, while the roads become deserted by evening. Moreover, those going out in the morning for a walk cover themselves in woollens. As a result, the chances of snatchers targeting them are less. But that doesn’t mean that the police are sitting idle. We are alert and have also asked the residents to be vigilant, as criminals can strike at any moment,” another officer said.

Psychologists, on the other hand, attributed the situation to the seasonal change in the level of melatonin in human body. “Low temperature and sunlight increase the melatonin level and it has a tranquilising effect on an individual,” said Vinay Kumar, a psychiatrist and a senior office-bearer of the Indian Psychiatrist Society, Bihar chapter.

“During winter, it is generally seen that a person tends to become slow, sleepy and sometime even sedated. This happens because the level of melatonin in a human body increases as result of the sunlight and cold temperature. This could be one explanation for the dip in crime figures during the winter,” he told The Telegraph.