Living things, both plants and animals, have a biological clock that is extremely important for survival. The human master clock is located in the hypothalamus of the brain in a tiny region called the suprachiasmatic nucleus (SCN). The SCN controls what is known as the circadian rhythm, a 24-hour rhythm of the body.
The SCN interacts with many regions of the brain to control sleep, hormone levels, alertness, body temperature, digestive activity, immune functions, and other systems. It coordinates the various rhythms of the body to keep us going through the day. This biological clock works in many ways that we don’t even realize.
Specialized cells in the retina of the eye connect directly to the SCN. When the eye senses light, the SCN receives the message and starts body process going by telling the various systems what to do and when. When you wake up in the morning, the clock signals enzymes to start flowing for your first meal. Hormones raise body temperature and blood pressure so that you can face the day.
During the day, the biological clock starts various chemicals and hormones so they will be available and functioning when they’re needed. Therapeutic medicines work best when taken at certain optimum times according to the biological clock. At night the circadian rhythm in the SCN sends a message to the pineal gland to produce the hormone melatonin making us sleepy.
Three scientists have just received Nobel Prize in medicine for proving scientifically something we knew all along. The scientists share the 1.1 million dollar prize for proving that we really do have a biological clock. The fact that you are alert at certain times and sleepy at others is not just in your head.
In 1984 they sequenced the “period gene” which others had discovered in fruit flies in 1971. The gene controls the circadian rhythm which regulates the daily sleep and wake patterns of all creatures, including humans. Following up on that work, in 1998 they found that the gene encodes a protein called PER. The PER levels build up at night and drop during the day. This discovery enables scientists to understand the molecular makeup of the biological clock.
Learning more about our biological clock leads to some useful understandings, including when is the best time to take certain medications. It also relates to shift work, jet-lag, and school classroom times. The understanding of circadian rhythms can be incorporated into practical medicine and the body’s production of melatonin, a hormone that prepares us for sleep.
A group of sleep researchers a few years ago did some research on biological clocks. They sent a group of volunteers on a tent-camping trip to the Colorado Rockies. They found that people who work indoors where they are not exposed to outdoor light may need to have their biological clocks reset. When people are indoors during the day and exposed to electric lights at night, their clock can become out of sync. Exposure to strong artificial light at night can delay our master clock. That delays the production of melatonin at night, and then the melatonin level is still high in the morning when it’s time to get up.
The campers were only allowed to use campfires for light and no cellphones or flashlights. After spending a week away from artificial light and exposed to more daylight, the volunteers fell asleep earlier and woke up earlier. Their melatonin levels rose earlier in the evening and dropped earlier in the morning.
The recommendation of the researchers was to start your day with a morning walk and when you have to be inside open the shades to get exposure to some sunlight. You may find that you will sleep better and wake up more refreshed.