Contrary to what you may have heard, a circadian rhythm is not a drumming circle. A sleep gene, along with your body’s hormones, is influenced by sunlight and darkness and to some extent by exercise, eating and general lifestyle to create your sleep / wake cycle, or circadian rhythm. Simon Cowell may also affect your rhythm and either put you to sleep or keep you awake.
The morning light helps kick start the brain into wakefulness. This is one good reason to have dark window coverings in your bedroom, unless you want to get up at dawn. Full alertness usually only comes after nine and a half gallons of coffee.
Your circadian rhythm affects your alertness, how tired you are, your ability to perform physical and mental tasks and your body temperature (which goes down in the evening and rises before wakefulness). It also causes your neighbour to start cutting his lawn at 6am Sunday morning.
You can change your circadian rhythm to some degree to better suit your lifestyle and your body’s requirements for sleep. If you need to awake at 7am to allow you time to get ready to go to work and if you require the average 8 hours of sleep, then you should be going to bed 15-20 minutes before 11pm (the extra time is for winding down with light reading and for falling asleep).
If you find you have to get up earlier, try 6:30am and go to bed a little before 10:30pm. Adjust your time 30 minutes forward or backward until you find the times that work best for you. Stick with your new bedtime for a week before you change it again.
Keep to your sleep / wake rhythm during the week and on weekends. If you stay out late Friday or Saturday night dancing, drinking or delivering religious pamphlets, get up at your regular wake up time.