Dawn and dusk, the hours preceding sunrise and following sunset, are incredibly important as plant processes are regulated according to their endogenous biological clocks that operate on a circadian rhythm. Simply put, a plant’s internal clock tracks these time periods over a number of days in order to work out how long the day and night periods are likely to be.

Photosynthesis, the process of collecting and storing the energy necessary to grow, takes place during daylight hours, while respiration, the process of using this stored energy to grow, takes place at night. Transitioning between these two diametrically opposed processes is both energy and time consuming. In nature, dawn and dusk can last anywhere from roughly one hour to many hours, dependent on the season and proximity to the equator.

Both light intensity and spectral composition changes during dawn and dusk; it’s during these periods that plants shift between the two fundamental functions and determine the best time to prepare to shift back come morning or evening.

By mimicking this natural process, the sunrise and sunset setting on Optex luminaires allows plants to shift gradually, and more efficiently, as they would in nature. Without this facility, indoor plants would normally have to make the transition during full light or darkness, reducing the effectiveness of the process and wasting time that could otherwise be spent on either growing, or collecting the energy necessary to grow. Adding up the hours of grow time potentially lost over the entirety of a plant’s life cycle amounts to nearly a week’s worth of wasted hours!