Science

Night owl or early riser: it’s in your genes

by Tanya Harrington

Recent research has indicated that the inclination to get out of bed and tackle the day sooner rather than later may be influenced by genetics.

All living things follow biological rhythms as a means of survival – and the study of these rhythms is known as chronobiology. Alongside a number of other living organisms, humans work in the circadian rhythm, which spans the length of approximately 24 hours before repeating. By this cycle, people are regarded as being diurnal, which means we are active during the daylight hours and sleep at night. However, there are variations within this model, with some people naturally waking up earlier in the day than others. These variations are known as chronotypes. For example, if you are likely to wake up early in the morning and go to sleep early in the evening, your chronotype is known as ‘morningness,’ and if you are more inclined to wake up later in the day and go to bed further into the night, your chronotype is known as ‘eveningness,’ similar to the commonly used labels of ‘morning people’ and ‘night people.’

Findings from research by chronobiologists now highlight the possibility that your chronotype could be influenced by genetic factors. Genetic information, taken from customers at 23andme (a personal DNA sequencing service that allows clients access to information about their genetic blueprints) who identified as ‘morning people’ showed that the majority of them had similarities within 15 parts of their genomes, with 7 of these parts directly relating to the maintenance of the circadian rhythm.

As well as this, the research findings also showed that those who identified with the concept of ‘morningness’ appeared less likely to suffer from insomnia or depression – perhaps contributing to the stereotype of morning people being annoyingly happy and cheerful. But, when these findings were put through a Mendelian randomization analysis, no causal relationship was found between morningness and these traits – so, it could be likely that this is mere coincidence, or that with a lack of traits such as insomnia, people are likely to sleep better at night and so are more inclined to self-identify with morningness.

Age is also a factor in the identification with morningness, as the majority of 23andme customers involved in the study who claimed to be morning people were adults over the age of 60. As young people and adolescents are thought to need more sleep than adults, and often display behavioural signs of ‘eveningness’ due to hormonal differences, it could be that although they do not self-identify as morning people, they can still display similarities with them in their genome. Alongside this, many adults who do identify with morningness may not display genetic signs of it, but just need less sleep – meaning that the results of the study could be somewhat skewed and that there may be a different number of people who express traits cohesive to morningness than they show.

However, genetics are not the only contributing factor to sleeping patters, and changes in diet or routine may always help you go to sleep earlier and feel better in the mornings. Just perhaps go easy on overly zesty morning people – or avoid them until they’ve had some coffee – because apparently, they really can’t help it.

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