They turn the light from the sun into usable electricity, making for beautiful garden lighting that's totally free to run. But how do they actually work? I spoke to solar and electrical experts ...

But how do they work? And what do you need to know before ... those contain blue light to simulate the natural rising of the sun. Instead, SAD lamps are designed to shine concentrated, high ...

Whilst it's not known exactly what causes SAD the disorder has been linked to a reduction in exposure to sunlight ... morning ...