There are lamps that use LEDs, and there are mirrors that can amplify the effect of direct sunlight coming in through a window. Then there's "Daylight," the lamp that won the Red Dot Design award. It features LEDs, but those are reserved for nighttime use. During the day, the lamp's aluminum reflectors take even ambient light from the outside and amplify it to light up a room.
The genius of "Daylight," the work of Felix Wilden, is in those reflectors. Just .4mm thick, they are 98% reflective (compared to the 75-86% of the typical mirror, according to Wilden). Not only are they located on the lamp, some are placed on the outside of the building, adjusted to send any light that hits them directly to their co-workers on the lamp, which spread it around. The system takes full advantage of what the sun is pumping out, so even low or indirect light can suffice.
When it's time to turn on the LEDs, a light sensor calculates how much light needs to be generated to reach the desired level, so the user can keep energy use to a minimum. For bonus points, "Daylight" is largely recyclable (it is made mostly of aluminum), but why would you ever want to dismantle such a clever design?