Chronobiology Dr Viola Zulian


This is the summary I wrote at the end of November when I returned from Lille

I’m on the train and I’m coming home from the SFRMS National Congress of Sleep Medicine (Société française de la recherche de la médicine du sommeil) that took place in Lille, in the North of a France that was and still it is, obviously Flemish in every sense.

I am a neophyte of sleep medicine, I have no claims as an expert or a professional, but I have an eye especially used to look at the subject from multiple points of view.

When I face a weight problem, I always support the thesis of the tripod: the overweight depends on how we eat, how we manage our daily stress and third but not least, how we sleep. An optimal sleep quality of at least 7 h per night in an adult subject makes life optimal.

During these 3 days I realized that each of us has a genetic imprinting regarding sleep habits: we can be owls or larks and it would be violence to forcefully change this biological clock. Those who have the habit of going to bed late, are certainly penalized by modern society because the tasks, be they professional or academic, will impose a shorter duration of sleep. It will therefore be obliged to a recovery recommended during the weekend so as not to incur a lack of sleep. I personally, I always woke up early, all my life. I have always studied better in the morning rather than in the evening and I remember that when I went to the study hall during the university, at 10:30 pm I turned off, with a margin of error of more or less 5 minutes. I always believed that morning people were winning. Well, this attitude has no relation either to success or to intelligence. It has been demonstrated on a particularly well-supported job in the UK.

Children have a rather neutral attitude, then in teenage, this watch is brought to hormonal issues (but also like to think about revolutionary ideals), forward a few hours. Then the teenager physiologically will begin to go to bed 2-3 h later and to wake up (forcibly) at the same time; this phenomenon takes the name of Social Jet-lag which has further deteriorated by an overexposure to the screens which I will discuss in future post. Once again, he will only have to recover during the week-end and we parents must support this recovery either in the morning or with the siestas whenever possible.

In the same way and for the same principle, it is necessary to respect elderly people who have a ”advancement phase“, that is: they go to bed early and wake up in the middle of the night. For them it is a problem because society does not help them endure this emptiness that surrounds them from 4 am to 8 am. My advice is to look for the activities themselves; it is not your fault to have different times. From a certain point of view I would rather consider it a luxury.

These habits are considered normal within a certain interval, there aren’t recommendations but I will set a 2-hour delta: 22h + or -2 h to fall asleep. All that is greater at this interval takes pathological variations that can be treated by a good sleep doctor with a little sleep hygiene, exposure to light therapy and melatonin administration. Do not mess up yourself, you would risk worsening the present situation.

Here is the fascinating world of chronobiology: our hormonal secretions follow the circadian rhythm (from circa diem in latin, almost a day of 24 hours); light and dark are indispensable switches for the suprachiasmatic nucleus from which the regulation of melatonin, cortisol, urinary volume and temperature will start. We treat it carefully because many things depend on it.