- Sleep has a survival value - different species evolved different types and patterns of sleep for different environmental needs. Sleep keeps animals dormant when activities vital for survival are not required.
- Predator-prey sleep (meddis (1979) - believs that sleep evolved to keep animals and children hidden when usual activities such as foraging, are not required. Therefore, prey animalsshould sleep less because they are at more risk and need to be alert and vigilant.
- Body size - smaller animals evolved a greater need to sleep, their metabolic rates being high and energy consumption rapid. Long periods of sleep help…