## 4 Discussion  
Over the last few years, awareness of the harmful effects of solar radiation on the human body has significantly increased. Society is increasingly using photoprotective preparations to protect itself from the negative effects of excessive sun exposure. Human skin is chronically exposed to sunlight from an early age, as some ranges of radiation can also penetrate glass and materials. In creating cosmetic recipes, more attention is being paid to the origin of raw materials and to the creation of natural cosmetics that contain more plant ingredients and fewer artificially obtained substances. Currently, the formulas of sunscreen preparations are being improved with substances that can absorb or reflect UV radiation without negatively affecting the skin [20]. Sesame oil is a rich source of unsaturated fatty acids, polyphenols, vitamins, and amino acids, which is why it has been used for centuries in nutrition and also in cosmetics to improve the appearance of skin, hair, and nails. It protects the skin against premature aging caused by several factors, including solar radiation, thanks to its antioxidative and anti-inflammatory properties [1; 2; 10]. There are many products on the cosmetic market that contain sunscreen. Unfortunately, most sunscreens only protect against UVB and less often against UVA. Depending on their composition, UV filters may either absorb (chemical filters) or reflect radiation (physical filters). Recently, many scientific publications have reported the harmfulness of other ranges of solar radiation, including infrared and blue light (HEV), which is also emitted by electronic devices [21; 22; 23]. The range of the solar radiation spectrum includes ultraviolet radiation (UVB (290-320 nm) and UVA (320-400 nm)) as well as visible light (400-770 nm) and infrared light (700-3000 nm). Ultraviolet radiation, which constitutes only 8% of this spectrum, is the most researchedand understood. In comparison, visible light makes up 39%, while infrared radiation makes up 53% of the total [23]. Ultraviolet radiation has mutagenic and carcinogenic effects. As a result of excessive and long-term exposure to ultraviolet rays, skin burns, erythema, and hyperpigmentation can occur, which can lead to the development of skin cancers, including melanoma. However, UV radiation is not the only type of radiation that has harmful effects on the skin. Infrared radiation (IR) and blue visible light (HEV) may also contribute to the acceleration of skin aging and the formation of skin defects, such as hyperpigmentation. Infrared radiation can penetrate the deeper layers of the skin, reaching the subcutaneous tissue, while ultraviolet radiation can penetrate the epidermis. IR rays are strongly absorbed by water in the tissues, causing them to heat up, which may lead to the rupture of capillaries in the skin, the formation of erythema, and the intensification of rosacea. Therefore, sunscreen cosmetics should contain substances that also protect against the harmful effects of other types of solar radiation [21; 22]. The study of the hemispherical reflectance of the skin before and after the use of sesame oil showed the lowest reflection value in the range of 335-380 nm, which corresponds to the range of ultraviolet radiation. According to the literature, the level of anti-UVB protection offered by sesame oil is defined as SPF 2 [9]. Therefore, we can clearly conclude that sesame oil does not provide significant protection against ultraviolet radiation. Since there were no significant differences in performance between the tested sesame oils, it is not possible to determine which preparation had the strongest effect on the directional reflectance of the skin. The tested sesame oils showed the greatest increase in reflectance in visible light ranges (400-540 nm, 480-600 nm, 590-720 nm) and near-infrared light (700-1100 nm, 1000-1700 nm, 1700-2500 nm).