It’s been found that people actually take kind of forced naps when awake for very long periods of time. Moments of nodding off where the body steals some sleep. This is why people crash their cars when they are tired, the brain shuts down to sleep from exhaustion, even though the thinking brain knows it is suicidal to sleep at that moment. When my husband lived in Bogata they changed the last call for alcohol to 1:00 in the morning, because they decided lack of sleep contributed to car accidents as mich as or more than alcohol. Their accident rate went down, even though the bars were open earlier, and just as full for the same amount of hours.
Anyway, lets say they actually do completely stay awake for 60 hours, it isn’t good for you, but it probably won’t kill them. They will likely sleep at least 15 hours the next day, and then another couple of days of long sleeps to catch up. They will be more prone to catching an illness during the 60 hours and days to follow. They will have impaired judgment, should not use power tools, drive, carry a baby, etc.
The vitamin D thing won’t have a big impact. First, we have no idea if they are dificient. If they get lots of sun in the summer, their D levels are probably still normal in winter. If they protect themselves from the sun all of the time with clothing or suntan lotion, their D levels are probably low all of the time, even in summer, unless they take vitamin D supplements, which would be the same all years. It’s pretty much impossible to get enough D just from food.