What are some examples of visual rhythms

Man and his biological rhythms

The sleep-wake rhythm of humans has adapted to the change of the seasons and above all to the course of the day over millions of years. Controlled by the brain, the same program is repeated in the human body.

All life on earth is organized in space and time. Many natural processes are rhythmic. The earth rotates around its axis in 24 hours and around the sun in 365 days. This creates day and night, summer and winter. The moon in turn rotates around the earth. It causes the sea tides with periodically recurring ebb and flow and, in interaction with the sun, determines the monthly rhythm.

The rhythm of nature

These cycles have had a major impact on life on earth. For example, many plants adapt their survival strategy to day and night. They open their flowers with the first sunlight. This makes their nectar accessible to insects, which in turn adapt their foraging flights to the rhythm of the plants and pollinate them. In this way they ensure their own continuity and that of the plant at the same time.

Humans have also developed a genetically internalized knowledge of time periods. For example, his body works very differently at night than it does during the day. This was necessary so that humans could survive in earlier times: during the day they had to be physically fit, go hunting and provide food, at night the body demanded sleep and relaxation. And even today the human organism is adjusted to the regular alternation of waking and sleeping phases. They make a decisive contribution to health and wellbeing.

In addition to the sleeping and waking phases, the human internal clock also controls heart rate, blood pressure and mood. Every cell and organ has its own rhythm that has to be regularly synchronized with the outside world. To this end, humans orientate themselves primarily to the brightness of the day and the darkness of the night.

Many human body functions are cyclical. Chronobiologists differentiate between three important categories, depending on the period:

  • Ultradian rhythms are each only a few hours, such as B. times of day or phases of hunger, sleep and wakefulness in infants.
  • Circadian rhythms are based on day and night. They last 24 hours (circa = approximately, this = day) and include e.g. B. Waking and Sleeping.
  • Infradian rhythms are longer than 24 hours, such as B. the change of seasons.

Sometimes in top shape, sometimes matt:
Man in the course of the day

Humans and their bodily functions follow annual and, above all, daily rhythms. Each cell and each organ controls its own time program. Breathing and heartbeat, waking and sleeping: all biochemically controlled functions have their individual highs and lows over the course of a day.

Just before waking up:  Body temperature, blood pressure and pulse rate increase.
About an hour later: The body produces stimulating hormones.
10 a.m. to 12 noon: Body and brain run at full speed, tricky brain teasers are easy, short-term memory is in top shape - the best time for exams and demanding activities. However, medical professionals also know that this is the most dangerous time for a heart attack.
12 noon to 2 p.m.: Digestion time: The stomach produces more acid so that lunch can be digested well. The stomach devours so much energy that the rest of the body gets tired. The person is dull and has a low performance.
Early afternoon: Second high performance for body and mind. In addition, the sensation of pain is at its lowest point; so an ideal time for the dentist appointment.
4pm to 5pm: Those who do sport are particularly productive; the ideal time for muscle building and conditioning.
6 p.m. to 8 p.m.: The body switches to the end of the day. When it gets dark, people get tired.
3 am: The organism reaches its absolute lowest point and is hardly ready to perform. Incidentally, the statistics recorded most natural deaths for this point in time.

Lack of light in winter

The time of year also influences the chronobiological rhythms of humans: Often they are less fit in winter and can concentrate less easily. He also eats more, so that body weight and blood sugar levels rise.

In addition, the seasons have a psychological effect. In areas with distinct seasons, people are more nervous in winter than in summer and are more often in a bad mood. A daily half-hour walk in daylight helps here. Circadian lighting has a supportive effect.

Some people are so stressed by the lack of light in the dark season that they can suffer from seasonal affective disorder (SAD) later. In Germany, every tenth adult is affected. Light therapy helps against the symptoms.

Need for sleep and age

In the course of life, the human sleep-wake rhythm changes. The internal clock of infants and toddlers is e.g. B. still determined by ultradian rhythms, i.e. phases of three or four hours each. By around two years of age, children develop pronounced sleep-wake phases; by the age of about five, they adapt day and night.

In the teenage years, sleep behavior changes again significantly: because with the onset of puberty, the internal clock ticks with a time delay. Young people get tired later in the evening and like to sleep longer in the morning, often for more than eight hours. At the start of school, they are often not quite fit and - in contrast to their teachers - suffer from “social jetlag”. At around 20 years of age, the need for sleep is reduced to a good seven hours.

With the beginning of the thirtieth year of life, the quality of sleep decreases continuously. People sleep more flatly and subjectively worse, although they go to bed earlier and more regularly than in previous years. When people are over seventy, they need less and less sleep at night - their bodies make less and less distinction between day and night. Although the need for sleep remains the same, the sleep-wake rhythm is increasingly decoupled from the external clocks, which is why many older people are reluctant to forego their afternoon nap.

Which chronotype are you?

Lark or owl? The human sleep-wake rhythm is firmly anchored in the genome - and not the same for everyone. Early risers and morning grouches can be recognized primarily by their sleeping habits.

The "owl": Still in the early morning with social jetlag

When the alarm goes off at 6 a.m., do you prefer to turn around in bed? Then you probably belong to the chronotype of the so-called "owl". Your internal clock runs much slower than that of other people; their day-night rhythm is sometimes only complete after 26 hours.

Owls therefore need some time to get used to the new day. If they are regularly torn out of their night's sleep early in the morning, which is subjectively far from over for them, they experience permanent “social jetlag”. Despite compensating external factors such as working hours or daylight, your organism adapts only poorly to the shorter rhythm of the earth's rotation. With every working day they accumulate an ever greater sleep deficit, which then has to be compensated for on the weekend.

The "Lark": wide awake early

Are you a passionate early bird? Then you are one of the so-called "larks". Your circadian rhythm is often complete after just 23 hours; the internal clock ticks a little faster.