system
Given the following post, respond as if you're commenting on Reddit:
human
Would flipping your body every 30 seconds for an hour get you just as tan as lying on both sides for 30 minutes each?
gpt
There are two ultraviolet lights at work in tanning: UVA and UVB. UVA causes the oxidation of melanin present in the skin, which causes a short term darkening of the skin. UVB triggers the production of melanin (which takes around 72 hours to have an effect).  
Although these processes are very different, they do both respond to damage from UV radiation, and the damage it causes is immediate and proportional to time (so it doesn't need to 'build up' before it begins having an effect). All this comes together to mean that it doesn't matter how you flip, but that it is the total elapsed exposure for each part of your skin that alters the tan.