A study in Edinburgh Sleep Centre found that avoiding light can fool our biological clock which can help to reduce jet lag. So wear sunglasses to reduce the exposure to light:
… Dr Chris Idzikowski, director of The Edinburgh Sleep Centre, said that without using sunglasses it took a day to recover for every hour of time difference travelled westwards.
…
“When passengers are travelling west it’s like a long day for the biological clock but when flying east, the clock tries to go into reverse which is obviously harder.”…
Sunglasses put jet lag in shade – [BBC.co.uk]
