Shift-workers benefit from blue blocking glasses because it protects the endogenous melatonin production by blocking out light at night, and creates a virtual darkness condition for the brain (1,2). Research also shows that their performance and alertness is not negatively affected (1,3). For the sake of cautiousness however, the authors do warn against the use in work that requires particularly high alertness (3).

1. Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect on performance during simulated shift work. Kayumov, L et al (2005) Journal of Clinical Endocrinology & Metabolism. 90(5):2755-61. https://www.ncbi.nlm.nih.gov/pubmed/?term=Blocking+Low-
   
   

2. Blue blocker glasses impede the capacity of bright light to suppress melatonin production. Sasseville, a et al. (2006) Journal of pineal research. 41(1):73-8.https://www.ncbi.nlm.nih.gov/pubmed/?term=Blue+blocker+glasses+impede+the+capacity+
   
   

3. Short-wavelength attenuated polychromatic white light during work at night: limited melatonin suppression without substantial decline of alertness. van de Werken M et al (2013) Chronobiology international. 2013;30(7):843-54. https://www.ncbi.nlm.nih.gov/pubmed/?term=Short-wavelength+attenuated+polychromatic+white+light+during+work+at+night%3A+limited+melatonin+suppression+without+substantial+decline+of+alertness.