Biological rhythms and sleep research are currently amongst the most important areas in public health. Sleep disorders have reached epidemic proportions and a large number of people worldwide suffer from chronic ‘circadian’ disruptions', i.e. conditions describing the discrepancy between the timing of our internal biological body clocks and that of our social environment. These include various forms of sleep disturbances and rhythm disorders, such as ‘social jet lag‘, i.e. the disruption of an individual’s sleep/wake rhythm due to social constraints. Social jet lag is directly comparable to ‘desynchronosis‘, commonly known as jet lag. Desynchronosis has been classified as one of the circadian rhythms sleep disorders and while the issue of jet lag is especially pronounced in frequent time-zone travellers, social jet lag and other sleep/wake related disorders affect a large number of people world-wide resulting in health problems, including sleep, cardiovascular, and metabolic pathologies, digestive disorders, impaired immune function, increased cancer risks, and a drastic decrease of mental and physical performance. Different ‘circadian phenotypes, i.e. ‘owls’ and ‘larks’ respond differently to environmental challenges and there is convincing evidence that owls and larks differ in genetics, physiology, and behaviour. We have to consider at least two distinct ‘phenotypes’ in the human population, early circadian phenotypes and late circadian phenotypes and the consideration of these will become a central theme in human biomedical research and public health in the future.
Biological rhythms and sleep research are currently amongst the most important areas in public health. Sleep disorders have reached epidemic proportions and a large number of people worldwide suffer from chronic ‘circadian’ disruptions', i.e. conditions describing the discrepancy between the timing of our internal biological body clocks and that of our social environment. These include various forms of sleep disturbances and rhythm disorders, such as ‘social jet lag‘, i.e. the disruption of an individual’s sleep/wake rhythm due to social constraints. Social jet lag is directly comparable to ‘desynchronosis‘, commonly known as jet lag. Desynchronosis has been classified as one of the circadian rhythms sleep disorders and while the issue of jet lag is especially pronounced in frequent time-zone travellers, social jet lag and other sleep/wake related disorders affect a large number of people world-wide resulting in health problems, including sleep, cardiovascular, and metabolic pathologies, digestive disorders, impaired immune function, increased cancer risks, and a drastic decrease of mental and physical performance. Different ‘circadian phenotypes, i.e. ‘owls’ and ‘larks’ respond differently to environmental challenges and there is convincing evidence that owls and larks differ in genetics, physiology, and behaviour. We have to consider at least two distinct ‘phenotypes’ in the human population, early circadian phenotypes and late circadian phenotypes and the consideration of these will become a central theme in human biomedical research and public health in the future.