Your circadian cycle gets wacky without sunlight to regulate it. I've talked to cavers that say they need to set alarm clocks otherwise they will be inside the

Your circadian cycle gets wacky without sunlight to regulate it. I've talked to cavers that say they need to set alarm clocks otherwise they will be inside the cave for days without noticing (thinking it's hours), which can be quite dangerous if you're not getting hydrated. https://books.google.com.br/books?id=8WrmCAAAQBAJ&pg=PA154&lpg=PA154&dq=isolation+48+hour+sleep+cycle&source=bl&ots=9ZaGwdA2vt&sig=a0ADkx8aqGTKtTEJaFk7ghiR-rI&hl=en&sa=X&redir_esc=y#v=onepage&q=isolation%2048%20hour%20sleep%20cycle&f=false https://books.google.com.br/books?id=8WrmCAAAQBAJ&pg=PA154&l...