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ALAN Conference Series

ALAN 5 will take place from the 12.-14. Nov. in Snowbird, Utah, US.

Night Sky Data to the People!

A new website presents citizen science data

Touring Exhibition

Our touring exhibition with 15 posters can be borrowed for events!

'Loss of the Night' App

The 'Loss of the Night' app measures sky brightness! Take part in a world-wide citizen science project that measures star visibility and light pollution. The app is free!

City Night Time Lapse

This growing collection of time lapse videos of nights in urban centres provides insights how city lights change throughout the course of the night

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Life on earth is ruled by the constant rhythmic change of day and night, light and darkness. Under natural conditions all rhythms of the body are synchronised with each other and to the day-night cycle. But if an animal is kept in darkness, the rhythm deviates slightly from the 24-hours and starts to fun freely at an individual, endogenously generated pace. Depending on the species, the internal rhythms vary between 22 and 28 hours. This periodic length is known as circadian (latin for about one day). We can compare this endogenous rhythm with an internal clock ticking too slow or too fast. Synchronising the internal clock with the environment requires periodically occurring external signals, also called zeitgebers (exogenous cue).

Light as a zeitgeber
The strongest zeitgeber is light. Humans are more likely to be active when there is light, while the body is regenerating when it is dark. The hormone melatonin, which is only being produced during darkness of the night in the pineal gland, serves as a signal to switch between action and regeneration so that its concentration in blood rises and the human gets tired. Light blocks the production of melatonin. The signal diminishes when the difference of the light intensity between day and night decreases. As a result, internal clocks can no longer be correctly reset, ultimately leading to a disturbed synchronisation between organisms and their environment. Circadian rhythms are indispensable for life, finding a mating partner or prey animals and also for avoiding competitors or predators.

Projects in this field of research:

The IfADo researches the topic "Light pollution - chronobiological effects of artificial light on humans".