## 1 Introduction
Photosynthetic carbon fixation, which hinges on light energy, is acutely responsive to light intensity at specific wavelengths. Photoperiodism governs plants' developmental responses to the daily light-dark cycle, while photomorphogenesis orchestrates the profound effects of light quality on plant development and physiology [5; 12; 13; 14]. Secondary metabolism in plants is heavily influenced by external factors such as light intensity, light spectrum, day length, mineral nutrition, plant architecture, and temperature. In C. _sativa_, secondary metabolites serve critical photoprotective roles. Evidence reveals that light stress or manipulation can dramatically alter the plant's metabolomic composition. Adjusting wavelength composition can also significantly impact phytohormone activity, stimulating flowering, inhibiting stem elongation, or reducing plant height. Chloroplasts, the epicenters of light sensing, dynamically alter their ultrastructure in response to varying photoperiods. The quality, quantity, and length of light are paramount, influencing the excitation of Photosystem I (PSI) and Photosystem II (PSII), the linchpins of photosynthesis (Figure 1) [5; 12; 13; 14]. Moreover, light parameters can bolster plant resistance to drought and salt stress, and recent evidence underscores the impact of light duration on plant responses to pathogen infection. Light manipulation holds immense potential, capable of regulating various aspects of insect life history, presenting a powerful tool for insect pest management in controlled environments [5; 12; 13; 14]. The yield quantity and quality of infloresences in C. _sativa_ can be markedly enhanced within controlled environment cultivation systems, where all environmental parameters and cultivation practices are meticulously regulated. Indoor cultivation often becomes indispensable due to unsuitable climatic conditions, stringent regulatory restrictions, or a synergistic effect of both factors [5; 15]. Among the myriads of factors influencing successful indoor cannabis cultivation, light--encompassing photoperiod, quality, and intensity--remains paramount [5; 15]. To ensure uniform environmental conditions and produce a consistent product, there is a burgeoning trend towards cultivating cannabis in controlled indoor environments. Within these 'in-door' facilities, artificial lighting systems provide the requisite light, with fixtures tailored to vary in intensity and spectral composition [5; 15]. _Cannabis_, cultivated for both recreational and medicinal purposes, is recognized as a high-value crop predominantly grown within controlled environment production facilities, such as greenhouses utilizing natural light or growth chambers and vertical farms devoid of natural light [5; 15]. These cultivation setups facilitate consistent, year-round production. The propagation, vegetative growth, and flowering stages of indoor cannabis production exhibit distinct photoperiod and light-intensity requirements [5; 15]. Optimal post-vegetative stage morphology is contingent upon the production system employed by cultivators, which encompasses variables such as the length of the vegetative stage, planting density, substrate and root zone volume, and the type of trellising system implemented during flowering [5; 15]. Nevertheless, the overarching objective is to ensure high transplant success rates and robust vegetative growth. Maintaining rigorously controlled conditions is indispensable for the consistent production of medical cannabis, particularly concerning inflorescence yield and the concentrations of secondary metabolites [5; 15]. These controlled environment cultivation systems not only facilitate the optimization of growth conditions but also ensure the production of a high-quality, uniform product, thus meeting the stringent demands of both medicinal and recreational cannabis markets [5; 15]. In this review, we conducted a comprehensive examination of recent research focused on the impact of indoor light on the growth, development, and secondary metabolite production in _C.