Police and Fire Service Sirens

Over the past few months in Tottenham, North London (UK) - police and ambulance sirens can be heard blaring between 3am and 4am. The problem is even more pronounced around the Monument Way. At this time of the morning, the roads are almost empty, yet these men and women felt it necessary to disturb the rest of the sleeping residents of Tottenham. It would appear that they could not even care about the health of these people they serve. The flashing lights are even visible from my apartment - so it is possible that other motorists - well the few that are on the road can too. The irony is that I sometimes stay with friends in Richmond, south London and in Buckinghamshire and have seen police and ambulance vehicles with their lights flashing late in the night but without sirens blaring? So why this nuisance in Tottenham???