Table 2.

Clinical studies on UVA, blue light, and PBM and NO bioavailability.

Wavelength	Irradiance	Light source	Model	Mechanisms / Outcome	References
320-410 nm	20 J/cm2 for 22 min	UVA bulbs CW (Waldmann GH-8 ST unit)	Human volunteers (adult 18 men, 6 women)	UVA exposure of the forearm releases NO from storage in the epidermis, lowered blood pressure, and increased blood flow independently of NOS	[116]
350-400 nm	10mW/cm2 for 60 min (60 J/cm2)	UVA bulbs (Philips TLK 40 W/10R R-UVA)	Human volunteers (adult 4 men, 14 women)	Increased NO-related products in the skin, including (nitrate, nitrite, and RSNOs and RNNOs)	[117]
450 ± 5 nm	42mW/cm2 for 30 min (72 J/cm2)	UV-free blue light LED CW (Philips Light & Health)	14 healthy male subjects	UVA increased plasma NOx (nitrite, nitrate, and RXNOs) and blood flow and decreased blood pressure	[119]
455, 660, and 850 nm	50 mW/cm2 for 15 min	LED (RoseLab, Montreal, Canada)	Human forearms (adult male)	455 and 850 nm increased NO release from the treated skin	[122]
650 and 880 nm	30 min treatment per day, 3 times per week for 8 weeks	GaAs LED PW 584 Hz (RevitaMe d Infrared Light Therapy RL-1001SP device)	22 patients with the clinical diagnosis of type 1 (N = 2) or type 2 (N = 20) diabetes mellitus	NIR therapy improved peripheral protective sensation No change in plasma NO metabolite levels (nitrates, nitrites, and nitrosothiols)	[142]
890 nm	7 mW/cm2 (636mW/90 cm2) for 30 min	GaAlAs diode PW (292 Hz, 50% duty cycle) (Anodyne therapy, Tampa, FL)	Human arms of 15 healthy subjects (adult 10 men, 5 women)	Plasma NO metabolites (nitrite/nitrate) levels↑ The peak increase in NO occurred 5 mins into the treatment	[130]

UVA, ultraviolet-A; CW, continuous wave; GaAs, Gallium-arsenide; NO, nitric oxide, NOS, nitric oxide synthase; RSNOs, S-nitrosothiols; RNNOs, N-nitrosamines; LED, light-emitting diode; NOx, NO species; RXNOs, nitroso compounds; ND, not described; PW, pulse wave.