Can't sleep? > Human clock

Human clock

Different organisms (plants, animals, bacteria, etc.) have evolved since the dawn of time to synchronize their activities with the day-night cycle caused by the Earth's rotation.

Our body follows circadian rhythms on a 24-hour cycle, where biochemical, physiological and behavioral processes take place. These rhythms can be influenced by our environment; especially by light. These rhythms are controlled by our biological clock which is located in the middle of the brain at the base of the hypothalamus.

Besides the main biological clock, our body also has other peripheral clocks which are found in several organs such as the esophagus, lung, liver, heart, pancreas, spleen, thymus and the skin. The main biological clock acts as the �central controller�, which transmits to peripheral clocks - on a regular base - electrical signals to adjust their functioning.

For example, the information regarding time of the day (light or dark periods) as relayed by the eye travels to the master biological clock, and through that, the clocks in the rest of the body may be synchronized. This explains how the timing of sleep/wake, appetite or body temperature is coordinated by the biological clock.

Rock around the clock!

This graphic illustrates the circadian patterns typical of someone who rises early in morning, eats lunch around noon and goes to sleep at 10 pm. Although circadian rhythms tend to be synchronized with cycles of light and dark, other factors such as ambient temperature, meal times, napping schedule and duration and stress and exercise can also influence the timing as well.

What about jetlag?
With today�s flights, the transitions between time zones are so rapid that the change in the light-dark cycle (cycle of 12 h light/12 h darkness) is too great for the biological clock to entrain to immediately. This results in a disparity between the external and internal rhythms.

While our biological clock is readjusting, the desynchronisation between the internal rhythms and external environmental rhythms results in jet lag.

Symptoms of jet lag are:

Dehydration and loss of appetite
Headaches and/or sinus irritation
Fatigue
Nausea and/or upset stomach
Insomnia and/or highly irregular sleep patterns
Irritability This out of synch situation causes some disturbances.

For example; our low blood sugar is normally lower at night (inactive period) but, due to the transition to a new time zone we need to be active; therefore, we suffer from a feeling of nausea. The more time zones that are crossed, the more that jetlag effects worsen. Jetlag is also worse when traveling East rather than when traveling West.

Tips to lessen the effect of jetlag

Set aside at the beginning and end of each trip to allow the clock to adjust (0.75 days are needed per time zone on a westwards flight, while 1 day is needed per time zone on an eastward flight).
2-3 days before your departure, try to go to sleep a few hours earlier if you travel eastwards and a few hours later if you travel westwards.
Force yourself to adjust to the new time zone: after a westward flight try and stay up as late as possible, thinking in terms of what the time actually is.
Outdoor activity or exposure to bright light will help the biological clock adjust faster.