Mid-infrared light produces anti-ageing effects through resonant absorption by living organisms

Aging is commonly viewed as a consequence of cumulative molecular damage and declining stress resilience. However, this perspective overlooks the possibility that aging may primarily arise from an efficiency loss of integrated cellular operation. Here, we show that aging can be systemically prevented by enhancing cellular efficiency using frequency-specific mid-infrared (MIR) light, as revealed by organismal-, cellular- and molecular-level analyses of Caenorhabditis elegans. Remarkably, super-weak 34-THz MIR light (~1 W mm^-2) prolonged the median lifespan of worms by 60%, delaying aging onset and preventing abrupt "cliff-edge" mortality, without detectable thermal effects. At the cellular level, MIR exposure enhanced global gene transcription in parallel with the establishment of a mitochondrial state of high-efficiency energy metabolism, together preserving youthful cellular homoeostasis during aging. These cellular effects were associated with vibrational modes of phosphate groups in nucleic acids and mitochondrial phospholipids within the 33-35 THz range, providing a frequency-matched molecular context for MIR modulation. Together, our results support an efficiency-first, systemic anti-aging model in which frequency-specific MIR light enhances the integrated kinetic efficiency of cellular systems, spanning gene transcriptional dynamics and mitochondrial bioenergetic flux, rather than the activation of damage-repair or stress-response pathways. These findings advance our understanding of light-matter interactions in living systems and establish a non-biochemical, physical strategy for modulating aging.