There’s evidence that warm lighting aids sleep in humans. Now there’s a connection between the other kind of lighting, ‘blue light’, and depression. Blue light is the kind of light our computer and mobile screens commonly emit.
The researchers exposed lab mice to blue light for two hours every night for three weeks and then watched the mice closely to determine if the light exposure was having any discernable impact on their behavior. The researchers found that initially, the mice showed no signs of change at all. But after three weeks, the mice began to work less hard for a sugar reward and tried less hard to escape when presented with the possibility—both considered to be signs of depression in mice. The researchers also found that the depressive symptoms continued for up to three weeks, even after discontinuation of night light exposure.
And there’s some evidence of the cause
They found a specific kind of light receptor in the mouse retina that led to brain areas associated with mood: the nucleus accumbens and the dorsal perihabenular nucleus. When the researchers disconnected them, the mice did not become depressive due to exposure to blue light at night. The researchers also found that the pathways became much more active when processing blue light at night versus daytime—which, they suggest, explains why blue light during the day does not lead to depression.
Use warm lighting wherever you can. Ideally everywhere at home but especially in the rooms where you spend your evenings. Second, turn Night Shift on on your iPhones, iPads and Macs. In fact, on Macs, instead of Night Shift, use the excellent Flux, which progressively changes the tint on your screen as you get closer to bedtime. The Amazon Kindle Paperwhite, at least the first-gen, also emits blue light – so around bedtime it may be best to turn off the built in light and read in ambient warm lighting. And have a wind-down routine.