Circadian Rhythms

• A pattern of behaviour over every 24 hours
• Regulates a series of bodily processes
• Sleep/wake cycle
• Examples of endogenous pacemakers that control circadian rhythm include systems that release hormones such as melatonin, systems that regulate body temperature and systems that control metabolism and digestion
• The main system that controls circadian rhythms is the suprachiasmatic nucleus (SCN)
• These internal processes are influenced by exogenous zeitgebers - perhaps the most obvious of which is sunlight
• For example, the darkness of night is thought to trigger melatonin release, which makes you feel tired and want to go to bed