Sunshine brings happiness…Light is the most important trigger for our internal clock. Our eyes respond to sunlight and transfer information to a small, central area of the brain known as the suprachiasmatic nucleus which is similar in size to a grain of rice. There, information on light intensity is processed and transferred to the pineal gland. The interaction of these two parts of the brain coordinates the body’s activity, both during daytime and also during nighttime rest phases. In essence the regulation of our wake-sleep pattern and other time-dependent cycles occurs as a result of hormone release. Such hormones control, for example, the body’s temperature, blood pressure and metabolism.
Written in the genes…Animals and plants, besides humans, also have their own internal clocks which control their daily routines. This includes even simple, single-cellular organisms, including bacteria or yeasts and thus suggests that such regulatory mechanisms are very old in evolutionary terms. Although specialist scientists, known as chronobiologists are searching for explanations, the detailed molecular structure of biorhythms is still not fully understood. Despite this, hundreds of different genes which are activated and deactivated on a daily cycle, have already been identified. They have descriptive names such as “clock”, “period” or “timing” genes.
Mutations in these genes can cause our internal clocks to perform erratically. Betsy Thomas is living proof for that. She carries a mutation within a period gene which has shifted her internal clock by about four hours. Consequently, she wakes up at three o´clock every morning. By early afternoon, however, she is extremely tired and usually goes to bed at about 7 pm. Betsy shares this lifestyle with several other members of her family.
On „larks“ and „night owls“Not all the differences in biorhythms are as dramatic as the example of Betsy Thomas. In normal, everyday life, for example, we might encounter two very different patterns of individual timing. Some people are at their most energetic in the morning and wake up very early – the so-called “larks”. Others, the “night owls”, go to bed very late and sleep for longer in the morning. Being a “lark” or a “night owl” seems to be inbuilt within our genes. Such individual biorhythms are not generally in any way problematic – as long as we can live according to our preferred internal clock. If, however, we must adapt to unsuitable time schedules such as nightshifts, or when we have to start work early, this can impact upon our health. Sleep problems, heart issues or mental disorders can result and a possible link to cancer has even been suggested.
Spring is challenging – summer compensatesWhen winter has passed, we instinctively look forward to summer. However, some people are not necessarily reinvigorated by the sight of melting snow or the first flower buds appearing, but instead fall into a deep fatigue. It is hard for the body to adapt to the new light intensities and warm temperatures. People can therefore start to produce high amounts of the serotonin which can tire out the body. Increasing temperatures can also dilate the blood vessels which can be additionally exhausting. As soon as our body has fully adapted to the new conditions, however, we can start to enjoy the best time of the year.