While green plants may reduce stress, I don't think their absence can explain the effect observed here. Exposure to aircraft noise during sleep has been documented to cause endothelial dysfunction [0], which increases oxidative stress [1]. I think it sounds very plausible that increased oxidative stress over a prolonged period can cause neurological problems.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3844151/

[1] https://en.wikipedia.org/wiki/Endothelial_dysfunction