Summer babies' sunnier outlook: Season of birth can affect body clock, scientists find | Mail Online
By Fiona Macrae
6th December 2010
Being born in the summer could give you a sunny disposition for life. And a winter birthday might cast a permanent shadow over your happiness, scientists believe.
Experiments suggest that season of birth dramatically affects the way the speed at which the body clock ticks. A winter birth could leave it moving too slowly – affecting health and personality.
The intriguing theory comes from a study of mice exposed to varying amounts of light in the first months of life. Some were given summer conditions of 16 hours of light and eight hours of darkness per day. Others had only eight hours of daily light, to mimic the short days of winter. After they were weaned, they were kept in the same light cycle for several weeks or switched to the opposite one. Finally, they were plunged into darkness and watched to see how they would react.
Those reared in summer conditions kept to a daily routine, but those brought up in little light struggled to cope with the change, the journal Nature Neuroscience reports. Researcher Professor Douglas McMahon said: ‘The mice raised in the winter cycle show an exaggerated response to a change in season that is strikingly similar to that of human patients suffering from seasonal affective disorder.’
Further research is needed to see how quickly after birth the biological clock is set and whether the effect is temporary or permanent. Despite this, the finding raises the intriguing possibility that the amount of light to which the human brain is exposed in the first weeks or months of life affects mood.
The professor said: ‘Our biological clocks measure the day length and change our behaviour according to the seasons. Several studies show that people born in the winter months have an elevated risk of mood disorders such as seasonal depression, bipolar depression and schizophrenia – all of which are associated with disruption of normal circadian rhythms. Whether seasonal birth could impact personality and mood is speculative, but not too far-fetched. Even though this sounds a bit like astrology, it is not: it’s seasonal biology.’
Previous studies have linked winter births to food allergies, possibly because of lack of the ‘sunshine vitamin’ D. But being born in the summer can have drawbacks – such as an increased risk of short-sightedness. Is thought that sunshine interferes with the delicate development of the eye, making focusing difficult and distant objects appear blurred.
Another study of more than 1.5million children in the U.S. clearly showed that those conceived in the summer are less clever than other youngsters. It is thought that they receive more exposure to pesticides during the first few months of pregnancy – a critical time for brain development.
By Fiona Macrae
6th December 2010
Being born in the summer could give you a sunny disposition for life. And a winter birthday might cast a permanent shadow over your happiness, scientists believe.
Experiments suggest that season of birth dramatically affects the way the speed at which the body clock ticks. A winter birth could leave it moving too slowly – affecting health and personality.
The intriguing theory comes from a study of mice exposed to varying amounts of light in the first months of life. Some were given summer conditions of 16 hours of light and eight hours of darkness per day. Others had only eight hours of daily light, to mimic the short days of winter. After they were weaned, they were kept in the same light cycle for several weeks or switched to the opposite one. Finally, they were plunged into darkness and watched to see how they would react.
Those reared in summer conditions kept to a daily routine, but those brought up in little light struggled to cope with the change, the journal Nature Neuroscience reports. Researcher Professor Douglas McMahon said: ‘The mice raised in the winter cycle show an exaggerated response to a change in season that is strikingly similar to that of human patients suffering from seasonal affective disorder.’
Further research is needed to see how quickly after birth the biological clock is set and whether the effect is temporary or permanent. Despite this, the finding raises the intriguing possibility that the amount of light to which the human brain is exposed in the first weeks or months of life affects mood.
The professor said: ‘Our biological clocks measure the day length and change our behaviour according to the seasons. Several studies show that people born in the winter months have an elevated risk of mood disorders such as seasonal depression, bipolar depression and schizophrenia – all of which are associated with disruption of normal circadian rhythms. Whether seasonal birth could impact personality and mood is speculative, but not too far-fetched. Even though this sounds a bit like astrology, it is not: it’s seasonal biology.’
Previous studies have linked winter births to food allergies, possibly because of lack of the ‘sunshine vitamin’ D. But being born in the summer can have drawbacks – such as an increased risk of short-sightedness. Is thought that sunshine interferes with the delicate development of the eye, making focusing difficult and distant objects appear blurred.
Another study of more than 1.5million children in the U.S. clearly showed that those conceived in the summer are less clever than other youngsters. It is thought that they receive more exposure to pesticides during the first few months of pregnancy – a critical time for brain development.
