Red light vs. blue light vs. multi-spectrum—what should I buy?

Reviewers across beauty and skincare publications generally recommend red/near-infrared for anti-aging (collagen, fine lines, tone) and blue for active acne. Multi-spectrum masks like the Shark CryoGlow and iRestore Illumina cover both, which makes them more versatile for combination concerns, though some specialist-community commenters argue a single-wavelength mask with proven irradiance beats a multi-mode mask with weaker output.