Board Thread:Questions and Answers/@comment-31619119-20170328142312/@comment-28251580-20170328203124

That is answered in Volume 9: If this is Underworld, the FLA mechanism is probably still working. If the rate is three times, my actual sleep time should be less than 3 hours. If it’s a fantastical idea like what I had yesterday such that it’s accelerated to 1000 times, it’ll mean that 8 hours is actually the equivalent of less than 30 seconds. Can such a short time really cause the mind to be so awake?

Basically you convert 8 hours into seconds (8*60*60, for minutes and seconds) and you get 28800 seconds. Since the time is accelerated a thousand times, we divide it through 1000, which gives us 28.8 seconds.

If we transfer that to a year, we have 365.25 days, as such the formula becomes (365.25*24*60)/1000 for the amount of minutes that pass in the real world when 1 year in Underworld passes by. The results are 535.96 minutes, or 8.76 hours.

I doubt that the principle of a leap year exists in Underworld too, even then I left it this way so the example can be used for other cases too. Simply use 365 days if you don't want to bother with it. 2026, the year Alicization takes place, is not a leap year, by the way.