The glymphatic system is a glial-dependent waste clearance pathway in the central nervous system, devoted to drain away waste metabolic products and soluble proteins such as amyloid-beta. An impaired brain glymphatic system can increase the incidence of neurovascular, neuroinflammatory, and neurodegenerative diseases. Photobiomodulation (PBM) therapy can serve as a non-invasive neuroprotective strategy for maintaining and optimizing effective brain waste clearance. In this review, we discuss the crucial role of the glymphatic drainage system in removing toxins and waste metabolites from the brain. We review recent animal research on the neurotherapeutic benefits of PBM therapy on glymphatic drainage and clearance. We also highlight cellular mechanisms of PBM on the cerebral glymphatic system. Animal research has shed light on the beneficial effects of PBM on the cerebral drainage system through the clearance of amyloid-beta via meningeal lymphatic vessels. Finally, PBM-mediated increase in the blood–brain barrier permeability with a subsequent rise in Aβ clearance from PBM-induced relaxation of lymphatic vessels via a vasodilation process will be discussed. We conclude that PBM promotion of cranial and extracranial lymphatic system function might be a promising strategy for the treatment of brain diseases associated with cerebrospinal fluid outflow abnormality.

Sexual dysfunction (SD) is frequently encountered in patients suffering from depression. There is a bidirectional relationship between various types of SD and depression, so the presence or treatment of one condition may exacerbate or improve the other condition. The most frequent sexual problem in untreated depressed patients is declining sexual desire, while in treated depressed patients it is difficulties with erection/ejaculation and with orgasm. Numerous classes of neuropsychiatric medications, commonly used in depressed patients—such as antidepressant, antipsychotic, alpha sympathetic, and opioid drugs—may cause SD. Photobiomodulation (PBM) therapy, also called low-level light/laser therapy, is a novel neuromodulation technique for neuropsychiatric conditions, such as depression. Transcranial PBM (tPBM) targets the cellular metabolism—through the mitochondrial respiratory enzyme, cytochrome c oxidase—and has numerous cellular and physiological beneficial effects on the central nervous system. This paper represents a comprehensive review of the application of tPBM to SD, coexisting with depression or induced by antidepressant medications.