https://www.researchgate.net/publication/375039349_Mechanical_stimulation_of_human_hair_follicle_outer_root_sheath_cultures_activates_adjacent_sensory_neurons
The article contains considerable science suggesting that stimulating hair follicles with massage may stimulate hair growth. Great care must be taken to avoid pulling on the hairs during massage, as the miniaturized hairs are easily pulled out.