In chapter 14 what is so bad about 3:00 am?

Check out this quote from the text,

But three, now, Christ, three A.M.! Doctors say the body’s at low tide then. The soul is out. The blood moves slow. You’re the nearest to dead you’ll ever be save dying. Sleep is a patch of death, but three in the morn, full wide-eyed staring, is living death! You dream with your eyes open. ch 14