A 2013 published study of 41 males aged 18 to 48 years showed that laser hair treatment provided a significant 39% increase in hair growth over 16 weeks!1
A key to optimum results is consistent early treatment over a period of time, similar to laser face treatments, with lasers of a specific power and wavelength.
1 The growth of human scalp hair mediated by visible red light laser and LED sources in males. Lasers Surg Med. 2013 Oct;45(8):487-95. doi: 10.1002/lsm.22173. Erratum in: Lasers Surg Med. 2014 Apr;46(4):373. PMID: 24078483.