Melanopsin blocker

A wearable device, comprising:

• one or more windows positioned to allow light from a light source to propagate toward a position of a wearer's eyes;
• and
• a spectral filter that comprises a coating positioned on one or more sections of the one or more windows,
• wherein the spectral filter includes a multi-layer stack of dielectric material with alternate high and low indices of refraction such that a layer having a high index of refraction is positioned above or below a layer having a low index of refraction, and a layer having a high index of refraction is positioned above or below a layer having a low index of refraction,
• wherein a number of the layers and a thickness of each layer are selected to provide designed transmission and blocking characteristics to block circadian-active spectra while allowing spectral content outside of the circadian-active spectra to pass through the spectral filter,
• wherein the designed transmission and blocking characteristics include a contiguous blocking region within 455-495 nm band of wavelengths with a tolerance to within at least ±5 nm, and two contiguous transmission regions, a first one of the contiguous transmission regions extending below 455 nm and a second one of the contiguous transmission regions extending above 495 nm,
• wherein the spectral filter is configured to block 98-100% of the spectral content in the contiguous blocking region, and transmit 80%-100% of the spectral content in the contiguous transmission regions, and
• wherein the contiguous blocking region extends from 455 nm to 495 nm, the first contiguous transmission region extends from 300 nm to 455 nm, and the second contiguous transmission region extends from 495 nm to at least 700 nm, all with a ±5 nm tolerance.