You might confidently label yourself a night owl or a morning lark, but groundbreaking research suggests our sleep-wake preferences are far more nuanced. Experts now propose that people actually fall into one of five distinct camps, rather than the traditional binary classification, when it comes to their fundamental sleeping patterns.
A New Framework for Understanding Sleep
A team of neurologists and psychiatrists has identified three specific subtypes of 'night owl' and two types of 'morning lark'. This sophisticated categorisation was achieved by employing an artificial intelligence algorithm to analyse data from more than 27,000 participants in the UK Biobank health study. The findings, published in the prestigious journal Nature Communications, provide a much deeper understanding of how our biological clocks influence our entire lives.
The Three Faces of the Night Owl
Contrary to popular belief, not all night owls are the same. The research delineates three clear groups:
- The High-Performing Night Owl: This group tends to excel at problem-solving and demonstrates faster reaction times. They often enjoy a drink, may drive faster, and are more likely to have children. However, they can struggle with emotional regulation.
- The Energetic, Risk-Taking Night Owl: Typically men, these individuals love social groups, are very physically active, and enjoy drinking alcohol. They are characterised by risk-taking behaviours and, like the first group, tend to be heavy drinkers and smokers, yet paradoxically show a relatively low risk of depression.
- The Sedentary Night Owl: This third group is more likely to be physically inactive, smoke, and faces a significantly greater risk of developing depression and cardiovascular problems. Their health challenges may be intrinsically linked to their late sleep schedules.
The Two Types of Morning Lark
Similarly, the early risers are not a monolithic group. The study separates them into two distinct categories:
- The Stable Morning Lark: This is the group many imagine when picturing early risers. They live stable lives with few risk-taking behaviours, are not likely to drink very much, and usually spend more time watching television. They tend to worry in everyday life but do not struggle with emotional regulation.
- The Tired Morning Lark: More likely to be women, this second group's early schedule appears to be a cause of persistent tiredness. They may struggle more with anxiety and are often more vulnerable to depression, despite their early waking habits.
Personalised Insights from Brain Data
The researchers did not rely on simple questionnaires alone. They looked at whether participants identified as night owls or early birds and then sorted them into these smaller groups based on profound similarities in their brain structures and neural connections. This was combined with detailed data on personality traits, behaviours, and physical and mental health.
Le Zhou, a neuroscience and data researcher from McGill University in Canada who led the study, emphasised the importance of this subtyping. 'Two people who both prefer late nights can have very different brains, lifestyles and health-related behaviours,' Zhou explained. 'By identifying subtypes, we can better understand why some people thrive on late schedules while others struggle, and why being an early riser doesn’t guarantee good health.'
This research moves the conversation beyond simplistic sleep advice. 'Depending on your subtype, you might need to focus on curbing impulsive behaviour, staying active or getting the right social support, rather than simply changing your bedtime,' Zhou concluded. The study ultimately reframes our understanding of chronotypes, offering a more personalised lens through which to view sleep, health, and daily functioning.
