Red Light Therapy for Cerebral Palsy: Scientific Evidence

In 2016, an observational study measured how laser therapy affected the jaw muscles of 30 children with cerebral palsy in São Paulo, Brazil. The jaw muscles on both sides were treated with 808 nm low-level laser light at 120 mW, 3000 mW/cm², 3 J/cm², and 2.4 J for 20 seconds per session, 6 times across 21 days. Mouth opening appeared to widen, and bite force appeared to fall in the weeks during and just after treatment. By the 6th week after treatment ended, both measures had returned to where they were before the first session.

40 children aged 1 to 4 with spastic cerebral palsy affecting one side of the body took part in a 2016 randomized controlled trial of laser acupuncture at a university in Cairo, Egypt. All received physiotherapy for 3 months, with 20 also given 650 nm light at 50 mW and 1.8 J/cm² for 30 seconds at each of 4 treatment points on the arms and legs, twice a week. The trial found lower muscle tone at the wrist and ankle in the group given laser acupuncture than in the group given physiotherapy alone. Range of movement and the total score on a standard measure of gross motor function showed no significant difference between the groups.

3 of 4 children with severe cerebral palsy showed a rise in a blood marker of bone building 1 month after starting treatment in a 2014 observational study of low-level laser therapy (LLLT). The 4 children received 810 nm light at 100 mW and 9610 mW/cm² for 60 seconds per session over 18 to 24 days, an average of 22 days, applied to the neck, the muscles alongside the upper and lower spine, a nerve behind the knee, and 2 treatment points on the limbs. A marker of bone breakdown fell in 3 of the 4 and stayed low 10 months later, while a hormone that regulates calcium dipped temporarily in all 4. The bone-building marker appeared to return close to its starting level by 2 months, so the effect on bone formation looked short-lived.

This 2004 observational study described 2 children with spastic cerebral palsy whose lower lips had been injured by involuntary biting. Both were treated with 685 nm low-level laser light at 190 J/cm², given twice 24 hours apart and then twice more at weekly intervals, applied to the injured lip and the lining inside the mouth. According to the report, inflammation and swelling were significantly reduced by the following day, along with pain and muscle stiffness. At the 14-day check, the report described the wounds as well advanced in healing.

Across 8 studies covering 80 participants drawn from 534 records, a 2024 systematic review examined laser therapy for muscle stiffness in children with cerebral palsy (CP). The review searched 4 research databases, limited itself to English-language studies of children, and used standard tools to rate how well each study had been conducted. The included studies used 620 to 780 nm and 780 to 1400 nm light for 40 seconds per session across 28, 30, and 42 days. The review concluded that low-level laser therapy (LLLT) showed promise for reducing stiffness, with some of the included studies also reporting less pain and greater muscle strength. It cautioned that missing treatment details, differing methods, and a shortage of objective measurements weaken what can be drawn from the evidence.