Researchers have long been trying to discover the mysteries of the brain, as well as target areas within to control behaviors. Optogenetics might be a relatively unknown area of neuroscience. Researchers inject tiny LEDs into the brain to control behavior article tells that for almost 15 years, scientists have been experimenting with optogenetics, a new way of studying the brain that uses light to control precise neural activity in freely moving animals. The challenge has been delivering light to exact regions deep in the brain. Researchers develop ‘wireless optical brain router’ to manipulate brain cells article tells that Kendall Research has created wireless prototypes that weigh just three grams (0.11 ounces) that can controls LEDs that can can be attached to the rodents: Tiny Injectable LEDs Manipulate the Brain With Light. Tiny Wireless LED Implant Can Activate Reward Centers in the Brain.
There has been also news on the effect of light to human brain. It is known that sitting near suitable bright light can be beneficial to people who live in areas where there is very little sunlight on winter. Finnish company Valkee says that the light does not need to go o eyes to have the same effect because human brains have some photosensitive parts, and they say they have scientific evidence for that. Valkee has been making some time special “headphones” that send light to human brains through ears. VALKEE Bright Light Headset sends photosensitive regions of the brain through the ear canal. There has been some discussion on are those really effective or not.
If you think that the products from Valkee are two expensive (around 200 euros) and looking for a cheaper DIY approach (how they can be so expensive when you just need two LEDs in ears), then take a look at metku.net article Valokkeet. It tells you how you can build your own light headphones from two LEDs and old headphones (for just few euros). At the moment Valokkeet article seems to be available only in Finnish, but you can always use Google translate to get English translation.