In one aspect, the present disclosure comprises a housing, a first directional light source, and a first driver. A directional light source is used, as opposed to an omnidirectional light source, since the intent is for the present disclosure to shine its light directionally to the eyes of a user. The housing houses the first directional light source and the first driver. The first driver is configured to drive the first directional light source to generate a fixed first light output. The first directional light source has a first melanopic ratio >0.80. A high melanopic ratio >0.80 is critical for ensuring the light source could provide adequate circadian stimulus to a user during daytime, therefore enhancing the circadian entrainment of the user. Color rendering index (CRI) or the color temperature of the first directional lighting is not directly correlated to the circadian entrainment, and thus are not used as a qualifying factor in selecting the first directional light source. Moreover, the first directional light source is configured to provide at least 50 equivalent melanopic lux (EML) at 60 cm at 0-degree lighting zone. The 0-degree lighting zone refers the light emitted out of a light source at 0-degree horizontally. The 50 EML is chosen as the minimal light output level for the first directional light source. This 50 EML falls below what is required by IWBI lighting requirements, which states >150 EML for work areas. This is because it is assumed that there exists a primary light source in an environment where the present disclosure is used, and the purpose of the present disclosure is meant to supplement to, rather than replace, the primary lighting source in the environment. When the primary light source provides a low EML to a user, it is foreseeable to use the present disclosure with its first directional light source having >50 EML at 60 cm at 0-degree lighting zone, e.g., 100 EML or even 150 EML. The 60 cm distance at 0-degree zonal light implies the present disclosure will be use in a close distance from the eyes of a user, for example, the present disclosure may be placed above a computer monitor or a laptop computer, and the light emitted out of the present disclosure shines directly into the eyes of the user. Lastly, the present disclosure is configured to shine a light of the first directional light source horizontally to the eyes of the user, thus providing an effective vertical lux to the eyes of the user.