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Lower Brain Connectivity Makes the Working Day Tougher for Night Owls

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Did you wake up bright and bushy-tailed this World Sleep Day? Or did you throw your slippers at your 6.30AM alarm and then fall back asleep whilst having a shower? If the latter option seems more familiar, you might consider yourself a night owl. New research from the University of Birmingham explains why you can now tell your boss that you arrived at work four hours late because that’s just how your brain is wired (the research did not investigate whether you would still be sacked for this, but odds are not good).

Working together with scientists at the University of Campinas in Brazil, and the University of Surrey, Birmingham researchers found that the brains of night owls have lower levels of connectivity in many brain regions which are implicated in the maintenance of consciousness.

The researchers also noted that these lower levels of brain connectivity were association with general poorer performance during the working day.

The study’s first author, Dr Elise Facer-Childs, now of the Monash Institute for Cognitive and Clinical Neurosciences in Melbourne, Australia,  highlighted the wider impact of these findings in a press release: “A huge number of people struggle to deliver their best performance during work or school hours they are not naturally suited to. There is a critical need to increase our understanding of these issues in order to minimise health risks in society, as well as maximise productivity.”

Testing the Brains of Night Owls

The study, which was published in the aptly named journal SLEEP, looked at the brains of 38 volunteers, who were classified as night owls or morning larks (they exist, apparently!) by assessing the levels of the circadian rhythm hormones cortisol and melatonin in their volunteers’ saliva and measuring their sleep/wake cycles using an actigraph unit, a small measurement device worn on the wrist.

During testing, volunteers were scanned using MRI, and then assessed on a variety of attentional cognitive tasks at 2pm, 8pm and 8am the next day. Those smug morning larks reported being less sleepy during, and performed best on, the early morning tests, whilst night owls reported being most awake during the 8pm tests. Even then, the night owls’ attention performance wasn’t better than that of morning larks, showing that an ability to get up early provides benefits throughout the day.

The MRI scans backed up the cognitive tests, showing that functional connectivity of the default mode network (DMN), a series of interconnected brain regions that are usually active whilst the brain is awake and at rest and is particularly affected by lack of sleep, was lower for night owls throughout the day.

A Kinder, Less Tired Society?

What does this mean for your average night owl? Dr Facer-Childs said the findings might explain why naturally late risers struggle in the office: ““This mismatch between a person’s biological time and social time – which most of us have experienced in the form of jet lag – is a common issue for night owls trying to follow a normal working day. Our study is the first to show a potential intrinsic neuronal mechanism behind why ‘night owls’ may face cognitive disadvantages when being forced to fit into these constraints.”

Previous studies have already shown how hard night owls have it: they have a 10% higher risk of early death and may have a higher risk of type 2 diabetes and heart disease. Dr Facer-Childs says society might need to start being more accommodating to the sleepiest among us: “To manage this, we need to get better at taking an individual’s personal body clock into account – particularly in the world of work. A typical day might last from 9am-5pm, but for a night owl, this could result in diminished performance during the morning, lower brain connectivity in regions linked to consciousness and increased daytime sleepiness. If, as a society, we could be more flexible about how we manage time we could go a long way towards maximizing productivity and minimizing health risks.”