Dark spots, clinically known as hyperpigmentation, are primarily caused by the overproduction of melanin, the pigment responsible for our skin, hair, and eye colour. This process is triggered by specialised cells called melanocytes located in the basal layer of the epidermis. When these cells are stimulated by external or internal triggers, they upregulate the activity of the enzyme tyrosinase, which catalyses the production of eumelanin. This excess pigment is then transferred via dendrites to surrounding keratinocytes, eventually becoming visible on the skin's surface [1].
In the Australian climate, the most prevalent cause is chronic ultraviolet (UV) radiation exposure. UV rays penetrate the skin and induce oxidative stress, which activates a protective melanogenic response to shield the DNA of skin cells from further damage. This results in solar lentigines, commonly referred to as sun spots or age spots [2]. Other significant causes include hormonal fluctuations—notably oestrogen and progesterone—which can trigger melasma, and cutaneous inflammation. This 'post-inflammatory hyperpigmentation' (PIH) occurs after the skin suffers a trauma, such as acne or eczema, causing an influx of inflammatory mediators that inadvertently stimulate melanocyte activity [3].
From a biomedical perspective, the formation of dark spots is a complex biochemical cascade involving multiple signalling pathways. The process, known as melanogenesis, involves the hydroxylation of L-tyrosine to L-DOPA and its subsequent oxidation. While melanin serves an essential evolutionary role as a biological photoprotectant, its uneven distribution is often a sign of cumulative photo-ageing or systemic metabolic shifts [1].
Beyond UVR, the 'exposome'—which includes environmental pollutants and high-energy visible (HEV) blue light—has been shown to contribute to localised hyperpigmentation. These factors generate reactive oxygen species (ROS) that exacerbate the melanogenic pathway, making broad-spectrum protection and antioxidant intervention crucial for managing skin evenness [4].
To help manage the appearance of these pigment deposits, many of our clients turn to formulated solutions like the C-Veil Citrine Tonic, which utilises Ascorbic Acid and Niacinamide to promote a more radiant, even-toned complexion. For those seeking botanical support against dullness, the Cellular Thread serum also includes Licorice Root and Bearberry, ingredients traditionally valued for their ability to gently assist in maintaining skin luminosity.
FAQ
What is the difference between sun spots and melasma?
Sun spots (solar lentigines) are discrete, well-defined lesions caused primarily by cumulative UV exposure over years. In contrast, melasma presents as symmetrical, mask-like patches of pigment, usually on the cheeks, forehead, or upper lip. Melasma is heavily influenced by hormonal changes, such as pregnancy or oral contraceptive use, and is often deeper in the dermal layers compared to standard sun spots [2][5].
Can blue light from screens cause dark spots?
Recent dermatological research indicates that high-energy visible (HEV) light, or blue light, can indeed stimulate melanocytes, particularly in individuals with deeper skin tones. This occurs via the activation of the Opsin-3 (OPN3) sensor in the skin, which induces a more persistent form of hyperpigmentation than UVB radiation alone [4].
How does inflammation lead to permanent dark spots?
Inflammation triggers the release of cytokines, chemokines, and reactive oxygen species. These inflammatory mediators, such as leukotrienes and prostaglandins, stimulate melanocytes to increase pigment production. If the basement membrane of the skin is damaged during the inflammatory event, melanin can 'leak' into the dermis, where it becomes trapped by macrophages (melanophages), making the resulting dark spot much harder to treat with topical moisturisers or serums [3][6].
References:
[1] D'Mello SA, et al. Signaling Pathways in Melanogenesis. International Journal of Molecular Sciences. 2016;17(7):1144. doi:10.3390/ijms17071144
[2] Bonaventure J, et al. Solar Lentigos: Pathogenesis and Overview of Management. Journal of Clinical Medicine. 2021;10(23):5541. doi:10.3390/jcm10235541
[3] Kaufman BP, et al. Postinflammatory Hyperpigmentation: A Review of the Epidemiology and Clinical Management. American Journal of Clinical Dermatology. 2018;19(4):489-503. doi:10.1007/s40257-017-0333-6
[4] Regazzetti C, et al. Melanocytes Sense Blue Light and Drive Pigmentation through Opsin-3. Journal of Investigative Dermatology. 2018;138(1):171-178. doi:10.1016/j.jid.2017.07.833
[5] Handel AC, et al. Melasma: A Clinical and Epidemiological Review. Anais Brasileiros de Dermatologia. 2014;89(5):771-782. doi:10.1590/abd1806-4841.20143063
[6] Passeron T, et al. Mechanisms of Dark Spots and Strategies for Prevention. Journal of the European Academy of Dermatology and Venereology. 2019;33(S6):15-19. doi:10.1111/jdv.15949
Medical Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting any new skincare regimen. Content reviewed by a biomedical scientist.
