Skin texture and collagen density
136 volunteers, 30 twice-weekly sessions — roughness and collagen density both improved against controls
A randomized controlled trial enrolled 136 volunteers: 113 received 30 twice-weekly sessions of red light at 611–650 nm, normalised to about 9 J/cm², and 23 were untreated controls. Measured skin roughness and ultrasound-measured collagen density both improved significantly against those controls, and blinded reviewers confirmed the change from photographs.2
Fine print: the abstract reports significance, not percentages, and broadband light showed no advantage over red alone.







