The circadian rhythm is the human’s daily biological clock, with a cycle lasting about 24 hours (circadian means ‘about a day’ in Latin). Influenced by light and body temperature, the circadian rhythm affects the release of hormones, cell regeneration, body temperature, appetite, alertness and sleep.The main circadian clock in humans is a part of the brain called the suprachiasmatic nucleus (SCN) located in the hypothalamus. The SCN receives information about the length of night and day from the light passed through the retina, interprets it and passes it on to the pineal gland. The body begins its active cycle in response to increasing light in the morning by producing the hormones serotonin, adrenalin and cortisol. Cortisol jump starts our body to wake up and get moving.
In the evening, as light begins to fade, the pineal gland begins to convert serotonin to the sleep-inducing hormone melatonin, the body cuts back on active hormones and body temperature starts dropping. Melatonin continues to be released throughout the night until the brain perceives light through our semi-translucent eyelids, starting the cycle over again.
Can it lose its balance?
The body’s clock can get out of sync with the normal 24-hour period due to environmental changes (light or temperature), travel, illness or changes in daily routine such as shift work. Anybody who’s traveled through time zones knows that when our rhythm is off, we experience fatigue, insomnia, changes in appetite, disorientation, and disruptions to our digestive system also known as jet-lag.
How does this affect our immune system?
Certain immune cells increase during sleep; making the night the most important time for recuperation and healing. Also, melatonin is one of the body’s most powerful antioxidants and removes free radicals and other toxins from our cells. If we aren’t getting enough quality sleep, our body’s defenses can’t protect us from illness.
Maintaining rhythm
Stay awake during the day. Light has the biggest influence on our circadian rhythm. Reset your body clock by exposing yourself to bright light (natural light if possible) when you need to stay awake. Sunlight, daylight and artificial light coming from above has a better impact than light that enters our eyes from below.
Sleep in the dark. Block out light with dark curtains or eye shades.
Go to bed 2 hours after sundown. The ideal time for sleep is around 9pm. Sleep hormones are flowing faster about 2 hours after melatonin is first released, making it more difficult to stay awake.
Maintain a good bedtime routine. Help your body wind down at the end of the day by eating a light dinner, avoiding stressful television programs and releasing stressful thoughts by writing in a journal or preparing your to-do list for the next day. Create a comfortable sleeping environment with the right room temperature and as little light and noise as possible.
Wake up to bright light. When you wake, open the curtains and take in the natural light. If you don’t get much light, use a bright light or go outside for a few minutes. You can also use a sunlight alarm clock that, instead of a jolt of sound, uses light to gently wake you up.
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