Our body and our activity are governed by our biological clock, which sets the rhythm of our days. In particular, humans are subject to the circadian rhythm: a biological rhythm lasting 24 hours, which defines the alternation between wakefulness and sleep.

It is our internal clock that determines this cycle, influenced by many external factors such as social rhythms (work, rest, weekend, holidays, activities), food, exercise, or environmental factors such as light or sound.

The internal clock is a brain mechanism on which we cannot act consciously. On the other hand, we can act on the environmental factors that influence its activity, in particular light.

The role of light on sleep/wakefulness alternation

Light is a powerful synchroniser of our biological clock:

When we detect daylight, our body secretes hormones and neurotransmitters that keep us awake (noradrenaline, cortisol, etc.). Our sympathetic nervous system is then stimulated: our body is in a state of wakefulness, and ready for physical and intellectual activity. Our heart rate and respiratory rate are fast and vary significantly throughout the day.

Conversely, our body secretes a hormone called melatonin, usually at night time, that promotes sleep. Our parasympathetic nervous system then takes over: it is characterised by a general slowdown of the organs and encourages the body to rest. Cardiovascular and respiratory functions are conserved.

However, this balance is precarious and can easily be disrupted by certain elements and habits – such as lunch hours, evening sports activity, or looking at screens before going to sleep – which can hinder the production of the sleep hormone.

This can result in sleep disturbances that can have negative or even harmful effects on health in the long term.

Sleep and health

Sleep disorder figures have been steadily increasing for several years. In 2019, almost half of French people reported having sleep problems. Studies also show a reduction in sleep time to 6 hours 42 minutes on average in a week1, while the recommended amount of sleep for good health is 7 to 9 hours per night².

Lack of sleep poses a health risk, which is more or less harmful. Sleep influences changes in weight, for example. When we sleep well, we secrete a hormone that promotes the feeling of satiety called leptin. Conversely, when we sleep poorly or don’t get enough sleep, our body produces ghrelin, a hormone that accentuates hunger.

But lack of sleep can have more harmful effects such as obesity, hypertension, increased cardiovascular events and type 2 diabetes.

Terraillon and sleep

Based on this observation, Terraillon has developed several sleep aids aimed at understanding and improving your sleep and your sleeping time. Our sleep products (Homni and Dreamer) are developed in collaboration with the European Sleep Centre to ensure that you fall asleep quickly and naturally every day.

We mainly rely on light therapy because light is a powerful regulator of our biological clock, and therefore our sleep. In addition, our products use red light because unlike other colours (including blue light), it is the only colour that does not block the secretion of melatonin, a hormone that promotes falling asleep.


  1. BEH Study – Bulletin épidémiologique hebdomadaire 8-9 | 12 March 2019
  2. Sleep Health Journal. Nation sleep foundation’s sleep time duration recommendations: methodology and results summary. (January 2015). DOI: 10.1016/J.sleh.2014.12.010

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