What happens in our body at each hour... Discover your biological clock
Our body temperature also changes according to our biological clock. Whatever body temperature our biological clock requires at a given point in the day, we perceive the passage of time accordingly. When our body temperature is high, time passes more slowly. Even a few minutes can feel long to someone lying in a hospital bed burning with fever. Yet on a cool countryside walk, a person witnesses time passing without even noticing it.
The reason for this is as follows: Every person has a biological clock. Just like body temperature, blood pressure, heart rate, and hormone levels. This clock governs our body functions. It helps us be active during the day and sleep at night. The proteins produced and broken down during the 24-hour cycle of the biological clock play a role in the secretion of vasopressin, a hormone that regulates animal behavior.
Those who go on long trips know this very well: time zone differences upset the body's natural rhythm. In discomfort caused by jet lag, a person feels tired and complains of headache and lack of concentration. Mood shows ups and downs. In this state, a person eagerly awaits bedtime.
OUR IMMUNE SYSTEM ALSO HAS A RHYTHM
For example, people's sensitivity to pain is high in the morning hours. As the day progresses, sensitivity to pain decreases. The risk of heart attack is higher in the early morning hours than at other times of day. Biological rhythms can span weeks, like women's menstrual cycles, as well as months and seasons. Many animal species migrate during certain seasons of the year and mate only at certain times of the year. In the early morning hours, hormones and neurotransmitters become active to bring the body to a state of alertness. The cycle of certain enzymes can vary by 400% over 24 hours. Our immune system also has a daily rhythm. For example, when we catch a bacterial infection, our fever usually rises toward noon. In illnesses caused by viruses, however, fever tends to rise toward evening.
Our tolerance for and sensitivity to pain also change throughout the day. Toothaches in the early morning hours are felt four times more intensely than in the afternoon.
In an experiment conducted on volunteer subjects, subjects kept lying down in a room isolated from daylight for 24 hours were observed to have a biological rhythm divided into two 12-hour periods. On the second day of the experiment, a second biological rhythm emerged, lasting 4 hours and repeating itself throughout the day. As with infants and animals, subjects were observed to become sleepy every 4 hours throughout the day.
Now let's see how our body functions change over the course of a day:
06:00: The organism wakes up with the secretion of cortisol. This awakening is a signal for the body to gradually prepare to get up. Metabolism becomes active, making energy and protein available for the day's tasks.
07:00: The body is still in a weak phase.
08:00: This is when hormones begin to be secreted.
09:00: This is the hour when the body is vigorous and strong.
10:00: The organism is now ready for activity and movement: it is highly energetic, the body has reached its highest temperature, and our productivity is at its peak. For a short time, memory is in good shape, and one becomes creative and dynamic.
11:00: This is an hour in which our body is in top form. Our biological clock has programmed our body to be productive.
12:00: The body needs to rest. Attention decreases and sleepiness sets in. The amount of acid in the stomach increases. Blood in the brain decreases, because blood is used by the stomach to support the digestive organs.
13:00: The body has dropped considerably in form. Productivity is 20% below the day's average. All organs function at their lowest level. Only the gallbladder is active, digesting lunch.
14:00: We feel exhausted, because blood pressure and hormone levels have dropped.
15:00: Get ready for new tasks. Our energy has returned, and our memory is at full capacity. We approach a second peak in productivity, although this productivity is less than in the morning.
16:00: This is the best hour for sports activities. Blood pressure and circulation are in very good shape. It is also the best time for exercise.
17:00: Organ activity is at a high level. Our strength increases, and oxygen consumption rises. The kidneys and bladder work particularly hard. This is when nails and hair grow fastest.
18:00: This is a good hour for dinner: the pancreas is particularly active at this hour. Even the liver is more tolerant and resilient toward alcohol than usual.
19:00: Blood pressure and pulse generally become sluggish at this hour.
20:00: The fat level in the liver drops, and used blood flows back to the heart more than usual.
21:00: The digestive organs' daily task has come to an end. Anything eaten remains undigested in the stomach until morning, and this situation is dangerous. Remaining food attacks the mucosa in the intestinal area. For this reason, particularly those who are overweight should be careful about eating at this hour.
22:00: At this hour, white blood cells — our body's police force — are particularly active.
23:00: The organism stops secreting the stress hormone that was actively produced throughout the day. We calm down, relax, and unwind at this hour. This is a time of complete rest. Metabolic activity is at its lowest level. Blood pressure, heart rate, and body temperature drop.
24:00: While we sleep, skin cells work nonstop. They divide more frequently than during the day. The first dream phase begins at this hour, and we begin dreaming within the first half hour.
01:00: Our productivity is at its lowest level. Those working at this hour are more likely to make mistakes, because attention decreases significantly. There is also an increase in workplace accidents and traffic accidents at this hour. This is because the body has programmed itself for sleep. Under the right conditions, one falls into a deep sleep.
02:00: Drivers should be more careful at this hour. Because our vision and reflexes weaken. For this reason, most traffic accidents occur at this hour. Our body is extremely sensitive to cold.
03:00: This is a dark phase both physically and mentally. The secretion of the hormone melatonin makes us sluggish and quite indecisive.
04:00: We gain energy from the stress hormone. Heart attacks are particularly frequent between 4 and 6 a.m. Because blood pressure rises considerably, and the coronary arteries become strained quickly.
05:00: At this hour, the male hormone in the body is secreted at very high levels. The concentration of the stress hormone has activated us. This hormone rises to exactly six times its daytime value. In other words, hormone secretion is at its peak. Our body springs into action, and lost energy returns. Now our body is ready to begin a new day.
If you would like broader information about our biological clock, you can benefit from my books "Discover Life" and "The Magical Power of Sleep."
Hüseyin Nazlıkul