While activity patterns of some animals are guided strictly by light-dark cycles or circadian rhythms, others show more flexible behavior. For ectothermic animals such as snakes, the temperature of their surroundings is a key factor in their physiology, behavior, and ecology. Various other factors, e.g., hunger, reproductive behavior, ecdysis, prey availability, and predation risk, also influence a snake's patterns of activity, often in conflicting and unpredictable ways. Studies of sleep patterns in such animals with variable and irregular activity may yield insights into the functions of sleep.
Available at: http://works.bepress.com/charles_amlaner/27/