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Sleep, Genes, and Society: The Fascinating World of Night Owls and Morning Larks


Are you the type of person who is best friends with the snooze button and doesn’t see the appeal of waking up to watch sunrise? Or are you a fan of the proverb “Early to bed and early to rise, makes a man healthy, wealthy, and wise”? It is very likely that you already know whether you fit into the category of a night owl, tending to be more alert in the evening and going to sleep late into the night, or if you identify yourself as a morning lark, going to sleep early and waking up with the sun. If you don’t, chances are people close to you have already noticed it.

What makes someone a night owl or an early bird?

Firstly, it is important to note that these definitions, backed by several scientific studies, tend to fit more into a spectrum rather than a strict group with the same characteristics, and people can shift from a lark to an owl throughout their lives. Sleep experts generally accept that the differences in sleep patterns have developed over centuries, as when early humans lived in groups it was necessary to have someone always awake to watch over the group, specially at night. The task was distributed among different age groups: teenagers, more energetic and gaining strength, kept watch during the night. Then, the elderly and babies would wake up at first light and teenagers could go to sleep, and when full daylight arrived, working adults would take over the task.

To understand what makes a person fit into one of these two categories, it is vital to understand what the circadian rhythm is. Circadian rhythms are physical, mental, and behavioural changes that follow a 24 hour cycle and affect most living things. This system dictates multiple processes in the body, such as alertness and sleepiness, appetite, and body temperature. It answers mostly to light and dark, so it is aligned with the cycle of day and night. The human circadian system has been studied several times by interdisciplinary research teams and the predominant discovery is the presence of consistent variations in day-night patterns among individuals, commonly referred to as chronotypes. Although our chronotype influences our sleep schedule, it is worth mentioning that it does not influence sleep duration and quality.

Moreover, a recent international collaboration with universities and research organizations in the UK, the USA, the Netherlands, Germany, and Australia used data from 700 000 individuals and identified 351 genetic factors that influence our chronotype. Although some of these 351 factors directly affect the circadian rhythm, others are related to the brain and the retinal tissue in the eyes. One explanation for the factors linked to the retinal tissue is that the circadian rhythm is slightly longer than 24 hours, so this may explain how our brain uses light to daily reset our body, aligning our body clock to the Earth’s cycle. These genes in the eye might aid morning larks in detecting light and adjusting their body clock more effectively.

This 2020 study noted that these new identified genes may affect more than our sleep pattern. It discovered that early birds tend to have a better mental health than their counterparts, as well as a decreased risk of schizophrenia and depression. One hypothesis for this is that morning individuals are more in sync to the 9-to-5 structure of most societies. Furthermore, this study contradicted the previously theory that night owls were more prone to developing diabetes and obesity. Finally, this research also found a relation between the time of the day a patient with schizophrenia takes their antipsychotic drugs and the likelihood of some of the side effects, which led to questions such as “Will morning people respond differently to treatments for psychiatric illness than evening people?”. Although there isn’t a clear answer to this question yet, this study opened the door to ask more and better questions about the influence of our chronotypes.

Differences between the two

Besides the usual tendencies already discussed about night owls – staying up late and sleeping in, feeling their best later in the day and having more energy at night – this chronotype usually feels more tired after waking up early and has more difficulties staying alert during the day. On the other hand, early birds feel their best as the day begins, have less energy in the afternoon and evening and have a hard time staying up until later. However, several studies showed that these two types of people may present more differences in distinct parts of their lives.

- Income

Although there are no outstanding differences in cognitive and general health between the two chronotypes, a study noticed that night owls usually had higher salaries than their counterparts.

- Intelligence

Another study by the University of Sydney measured the intelligence levels of over 400 participants with tests regarding vocational skills, mathematical aptitude, reading comprehension, and other cognitive processing abilities. It found out that night owls tended to outperform morning larks on almost every test, having great disparities in terms of memory speeds. Moreover, night owls performed better than morning larks even if the tests were conducted in the morning, which might suggest that these individuals possess an overall higher IQ.

- Romantic behaviour

The University of Education Heidelberg in Germany conducted a study on 300 male participants analysing their sexual behaviour. They found that people with preferences for nighttime activities tended to have more romantic activities than early birds, and they also tended to have more extramarital relationships.

- Addictive behaviour

Several studies have linked being a night owl to engaging in addictive behaviours, being less likely to quit smoking, having a higher risk of developing a dependence on illegal drugs, and exhibiting greater vulnerability to the influence of alcohol. While this association may be connected to nightlife culture, given that during their most productive hours only certain establishments are open, researchers have still not identified the underlying cause of this tendency.

- Strength

A study compared the leg muscle strength of early birds and night owls throughout the day and discovered that while night owls had a peak in performance in the evenings, morning people’s strength tended to be constant during the whole day.

- Personality traits

However, the addictive behaviour mentioned before may be linked to a personality trait typical of night owls called “novelty seeking”, that is, a tendency to pursue new experiences with intense emotional sensations. On the other hand, morning larks tend to have higher levels of cooperation and persistence. This means that early birds are generally more diligent and agreeable than their counterpart, which makes them more proactive instead of reactive.

- Procrastination

Night owls tend to be more associated with procrastination and task avoidance during the day, compared to their counterparts. Moreover, new research from Sleep Score Labs, distinguished evening types as the one more prone to bedtime procrastination, that is, needlessly and voluntarily delaying the hour to go to bed, despite knowing it will be worse in the morning. Given this individuals’ higher energy levels at nighttime, they tend to postpone sleep to be able to have time for themselves that they might have missed during the day.

- Mood and stress

In 2012, the University of Toronto assessed a sample of 400 young adults about their current moods, considering the person’s chronotype. Researchers found out that morning people tend to be more positive and night owls presented higher levels of anxiety and stress. This might happen because the 9-to-5 schedule of our society suits more early birds, and given their propensity to wake up earlier, they may get prolonged exposure to natural light, which makes the brain release serotonin, the “happy hormone”.

- Creativity and analytical thinking

A study by the journal “Thinking and Reasoning” tried to determine the differences in creative and analytical thinking in early larks and night owls. The study concluded that in terms of analytical tasks, demanding problem-solving competences, was easily tackled by early birds during the day and by night owls in the evening. However, in terms of creative thinking, researchers learned that people would excel in their “off-hours”, when they were pushed beyond their comfort zones, which allowed their mind to explore more creative thoughts.

- Time maximisation

One significant distinction between the two chronotypes is at which time they maximise. In fact, a recent study focused on determining each group’s peak strength, realised that night owls’ energy levels peak at around 9 pm. This is due to the simultaneous peaking of their central nervous system and spinal cord excitability, which provides them with an energy boost at the end of the day. On the other hand, morning larks’ central nervous system and spinal cord excitability never peak at the same time. They end up experiencing a peak at around 9 am and then their energy levels progressively decrease throughout the rest of the day. So, while early birds are reaching their minimum energy, night owls are reaching their maximum, and don’t start to decline until they are ready to sleep.

Despite these differences, it does not matter which chronotype you are and at what hours you choose to go to sleep and wake up, as long as you are getting the recommended seven to nine hours of sleep each night. However, our society is tailored to fit more early birds, so, night owls might want to change into an early bird to fit into society more easily.

Is it possible to change from a night owl to a morning lark?

The short answer is yes. However, this will depend on the genes of the person and their willpower, and it is important to keep in mind that the genetic tendency and predisposition will continue to be there. Still, there are some techniques that might help.

- Morning Light Exposure

By controlling the timing and type of light we see in the morning when we wake up, as bright light can help to reset the circadian rhythm. It will also help to train other body rhythms such as blood pressure, heart rate and cortisol to be earlier. The trick is to expose your eyes to bright light as soon as you wake up, preferably natural light, but in case it is not possible, there are several products that simulate the morning light. Afterwards, you should continue to expose your eyes to brighter light throughout the morning.

- Evening Light Reduction

On the other hand, you should turn down the lights as much as possible in the evening, specially the closer you are to your bedtime. You should avoid the blue light from electronic devices and opt to read a book or play a card game before going to sleep.

- Timing of Daily Activities

Night owls tend to prefer to eat and exercise later. However, besides extending the hour you go to bed, this is associated with weight gain and higher obesity. Therefore, you should try to exercise more in the morning or early afternoon and avoid physical activity at the end of the day.

- Sleeping Pills

Avoid sleeping pills, as your goal is to change the biological clock and not to force sleep through drugs. However, if light is not working fast enough, taking a very lose dose of melatonin three hours before bedtime may help. To take it, you should already be in a dark environment and cannot be exposed to bright light afterwards.


To summarise, individuals tend to fall into the categories of night owls or morning larks, with differences in sleep patterns and daily preferences that are shaped by genetics and circadian rhythms. Various studies reveal several differences in other aspects of these two groups lives, such as romantic behaviour, addictive tendencies, personality traits and cognitive abilities. Both chronotypes can achieve well being and the recommended sleep duration regardless of the way they structure their day. However, our society tends to favour early birds with a 9-to-5 schedule. So, it might be important for night owls to adjust to a different sleep schedule by adjusting their exposure to light and the way they organise their activities throughout the day.

Written by Beatriz Pedro


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