We might misunderstand the concept of sleeping. We tend to do as much as possible during the day but can not avoid going to bed sooner or later. This is caused by a compound called adenosine. The level of this natural chemical substance is constantly growing while we are awake and dissolves in the body only during sleeping.

This substance is counting the lost sleep and indicates if there is resting needed. This way the body is forced to compensate for the lost sleep with a longer one. This feedback on a molecular level ensures that we could not get used to less sleeping than needed. This way we are not able to “owe” sleeping on a long run.

Our inner biological clock and the environmental factors determine the time when we feel sleepy and would like to go to sleep – mainly the darkness and lightness. As a matter of fact the biological clock is a group of cells in the brain which reacts to signs of light arriving in the eyes.

When night comes the biological clock starts to produce a hormone called melatonin. As its quantity is increasing in the body we feel more and more sleepy – this feeling is the strongest between midnight and 7 am. We might experience a similar feeling in a lighter form during the day between 1 pm and 4 pm. The melatonin production is increasing again for the second time which can make us sleepy.

Biological clock

Because of our biological clock we are the most awake during the day and the sleepiest during the hours of dawn. Human beings can perform their best during the day but in this fast world, working 24 hours a day, 7 days a week often requires working in night shifts. The 25% of all of employees are working at night and the third of those fights with sleepiness and suffers from hard sleeping.

As their working schedule does not harmonize with their biological clocks they are often sleepy during working hours and can hardly sleep during the daytime when it would be time for them to sleep. Tiredness can be dangerous for those working at night, the most of the work related accidents happen this time of the day. This kind of catastrophes have occurred for example at the nuclear power plants in Three Mile Island and Chernobil and at Exxon Valdez.

The risk of a traffic accident is higher at those who working in night shifts, for example when they go home from work. According to a survey an accident or nearly an accident has happened in case of 20% of the people working in night shifts and were on their way home from work. The possibility of health problems are higher in the case of the people working in night shifts like heart diseases, digestion problems, infections and mental disorders. These all are partially related to chronic lack of sleep.

Influential factors

Other factors might influence our demand of sleep. For example the production of cytokine cell-hormones. These are present in the body in some cases of infections and chronic inflammations. Their symptom is that the demand for sleep is increasing. During the time of rest the body can turn more energy to fight the sickness. According to new researches getting enough sleep is helping the immune system against infections as well.

People are led by their customs. One of the most hardly changeable custom is changing the cycles of being awake and sleeping which is helping us to control by many biological factors every single day. Therefore choosing the right time for traveling between time zones might cause big difficulties as well.
It might occur that according to biological stimulus caused by light it is 8 o'clock and one should be active but according to the body it is only 4 am and rest is needed. The result will be that one is tired all day long and both being awake and sleeping would cause difficulties. Because of all these reasons one would feel bad, will concentrate harder, nausea and retching might occur.