If there's one thing they forget to tell you about Antarctica, it's the fact that you won't be getting much sleep there. Time becomes a very elastic concept in summer on the continent—you can expect as much as 20 hours of sunshine a day, and regular markers such as mealtimes will vary according to the weather (for example, if the weather's good around lunchtime, the food will be delayed while you go ashore or do a spot of kayaking).
This means that insomnia (or what Antarctic veterans call "big eye") affects many people during the first few days of their voyage. Add to this the jet lag you've accumulated while flying to your point of departure, and you can expect to spend plenty of sleepless hours staring at the ceiling of your cabin. Bring an eye mask, and if that fails to do the trick you could always try a few swift glasses of Scotch.