sleep/wake cycle

• Circadian rhythms:

  Internal biological clocks that regulate various physiological processes and behaviours in animals.
• Circalunar rhythms: 

  Biological rhythms that are synchronised with the lunar cycle

  • approximately 29.5 days
• why do animals have these cycles?

  • predation
  • food availability
  • environmental conditions
  • social factors
  • body size and metabolism