They do not sleep in the human sense. They slow down and reduce activity to get into a ‘rest’ mode, with their eyes closed, but still awake sufficiently to known when oxygen levels drop and that it is time to surface to breathe.
They do not sleep in the human sense. They slow down and reduce activity to get into a ‘rest’ mode, with their eyes closed, but still awake sufficiently to known when oxygen levels drop and that it is time to surface to breathe.