Recently I have noticed that some cars following me at night are causing me to dip my rear view mirror to avoid being dazzled. I have not yet been able to identify any particular makes, but these cars generally have modern, steely-blue headlights. The problem however is with the height of the beams, not the colour. Traditional headlights stay fixed in the same direction as the car, but there seems to be some new technology that results in headlights operating normally for a while and then suddenly flashing at a much higher level, as if they are mounted in a bowl of liquid and the car has just gone over a rougher bit of road. I find it disconcerting and I have even started to re-position my wing mirrors at night to avoid glare. I don't think it is caused by use of the manual dipswitch, but perhaps you know what is happening? If it is a new type of headlight, have they been approved after tests only done when the vehicles are stationery?