Here is a book on light therapy. You can get as a cheap Kindle.
https://www.amazon.com/Ultimate-Guide-Light-Therapy-Near-Infrared-ebook/dp/B07FJNZ821/ref=sr_1_2_sspa?dchild=1&keywords=red+light+therapy&qid=1618806438&s=books&sr=1-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExNjFTNEwyWjdITFBVJmVuY3J5cHRlZElkPUEwNjg2MTc3QzFYN0ZZVUVZQTE3JmVuY3J5cHRlZEFkSWQ9QTAxNDUzNjJNU1pKN1A3QldNWEkmd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl