There's a reason casinos rarely have windows or clocks, they're engineered to make you lose track of time. But what if it's not just time you're losing? New research suggests that the lighting used in ...

Today, we have three types of headlights: tungsten-halogen, Xenon high-intensity discharge (HID) lights and light-emitting diodes (LED). Introduced in the 1980s, halogen are the cheapest.