I suffer from chronic insomnia, and I certainly didn't notice the afternoons and evenings spent on a pot of good oolong to be any worse than the same with herbal or rooibos.
Most Japanese green teas are steamed past the harvest time – lightly (gyokuro), or more thoroughly (sencha), or anywhere in between depending on the grade – and some varieties can also be roasted (e.g. yabukita). Japanese green tea generally requires milder water temperatures for a preparation. Typically, the higher is the grade, the lower is the temperature, e.g. from 60ºC for gyokuro and high grade matcha to 80ºC for sencha. Gyokuro and matcha, prepared at the right or slightly lower temperature, has a lot umami flavour with a little bit of sweetness in it.
Varieties of the Chinese green tea is either lightly roasted (without being steamed nowadays) or lightly fermented. They need higher water temperatures, typically in a range between 80ºC and 90ºC. High grade Dragon Well prepared at the 80ºC temperature has a unique flavour that I don't know describe, but it will have almost no flavour is a lower temperature is used.
Not to say they make it exactly the same, I wouldn’t know, but the origin is China.
I think in general it's safest to brew green teas at 175f. But I'm doing quick gongfu brewing sessions with a late-march sichuan green tea, and it tastes great at 205f. Less intense at the usual 175f, but picks up more subtle flavors.