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This article is evidence-based, verified by Ashleigh Willis, a Neuroscience Ph.D. candidate.
Psychologists have been able to identify patterns in personality. Additionally, some early research suggested that aspects of personality may be genetic.
Modern thinking suggests that personality is a more complex concept. Contemporary psychologists believe that personality can be affected by many factors. This includes biological and environmental contributions. Personality is thought to be a driving factor that predicts our health. This includes predicting depression, anxiety, and other psychiatric disorders. Research has also shown that personality can have a massive impact on our chances of developing sleep disorders.
Paradoxically, sleep quality is thought to be able to modulate personality as well. Short and long-term disruption to sleep can result in a variety of biological changes. As a consequence, our behaviors and personalities can be altered.
Psychologists have come up with many theories to explain personality. The most famous of these is a psychological trait theory called the Big Five personality traits. Sometimes this is also referred to as the five-factor model.
The model was designed in the 1980s and is still used today. The Big Five has become a foundational concept in psychology. In fact, in modern psychological practice, the Big Five often underpin clinical theories.
What are the Big Five personality traits? 🧠
The Big Five personality trait theory is composed of five broad personality factors. The acronym OCEAN can represent these.
Openness refers to how open people are to new experiences. Usually, people who score high in openness enjoy learning and experience new things. These types of people will often be curious and inventive. People who score high on openness tend to express emotions with ease. They are also more likely to hold unpopular beliefs.
Low scorers on openness will generally be more cautious about new experiences. These types of people may even prefer consistent routine and find change difficult. People who have low openness scores sometimes appear data-driven and calculated.
The general trait of openness is composed of a variety of sub-traits. These are:
- Aesthetic Interest
- Emotional Orientation
Conscientiousness marks a strong tendency toward self-discipline. Individuals who score high on conscientiousness are high achievers and strive for success. Sometimes very conscientious people may come across as stubborn.
People who score low on conscientiousness are generally more flexible and spontaneous. While these people can be high achievers, they rely more on spontaneous action than pre-defined plans. This can sometimes come across as unreliable.
Sub-traits of conscientiousness are:
The next big five personality trait is extraversion. Extraversion scores denote the level to which a person is externally oriented. Extroverted people gain a lot of joy from the external world and social situations. People who score high on extroversion are usually energetic, talkative, and pleasure-seeking. While extraverts enjoy socializing, the trait doesn’t always indicate “pro-social” behaviors.
Similarly, people who score low on extroversion aren’t necessarily disinterested in others. Instead, social measurements refer to how much a person enjoys time alone. People who score low on extraversion are reserved and enjoy a subdued lifestyle.
Extroversion includes many sub-traits:
- Positive Emotions
- Activity Level
Agreeableness reflects how concerned an individual is with social harmony. It also denotes their concern for the thoughts of others. People who score high in agreeableness find it essential to get along well with others. They avoid conflict and are generally kind, caring, and compassionate. Agreeable personalities also have an optimistic view of the world. This leads them to be trusting and trustworthy.
Conversely, those who score low on agreeableness are less concerned with the needs of others. These people can seem to be serve-serving or always acting in their interests. This means they may find themselves in situations of conflict more often.
Sometimes these types of people can seem challenging in a workplace environment. However, their argumentative nature can drive projects forward and achieve goals. They also perform well in careers such as law, science, and the military.
Agreeableness encompasses the personality sub-traits below:
The final of the big five personality traits is neuroticism. Neuroticism refers to an individual’s proclivity toward negative emotions. People who score high in neuroticism tend to experience negative emotions. Conditions such as depression anxiety are more frequent in top scorers.
In general, people with high levels of neuroticism have a lower standard of wellbeing. Neuroticism at high levels often impairs resilience to stressful situations. People who score high in neuroticism may also find that their defenses are easily activated. They experience many situations as threatening.
Neuroticism includes a variety of personality sub-traits:
- Proclivity for depression
The biological basis for personality 🧠
Personality is complex and still not fully understood by neuroscientists. We know that there are some biological processes and brain regions, which are crucial to personality. Neuroscientists have correlated some of the big five traits to features of the brain.
The main brain networks involved in personality composes the autonomic nervous system. These include fear and reward pathways that activate a variety of brain areas. The main brain regions which under personality appear to be the:
- Ventral tegmental area
- Nucleus accumbens
- Prefrontal cortex
These four regions compose a complex network that controls behavior and emotion. Differences in the connectivity of these regions may result in various personality differences. Notably, in autism, many of these regions appear to be dysfunctional. In particular, the prefrontal cortex exhibits imbalanced neuronal communication. This may contribute to alterations in the way these regions communicate and receive information. Ultimately, this could underlie some aspects of personality.
Brain communication relies on many different signaling molecules called neurotransmitters. Neurotransmitters are highly specialized proteins that flow between neurons and affect brain function. The primary neurotransmitters are:
Together these molecules act in synchrony to control behavior. The brain circuits linked to personality rely heavily on monoamine neurotransmitters. These neurotransmitters are Dopamine and Serotonin. Both of these are associated with big five personality traits, sleep, and autism.
- Dopamine is the primary neurotransmitter involved in the reward pathway. Dopamine underpins our feelings of motivation and drive. It’s the neurotransmitter that helps us work toward goals in search of a reward.
- Dopamine pathway activation is correlated with extraversion.
- Many diverse dopamine defects are associated with autism. Research suggests that dopamine deficits may be linked to hyperactivity and motor deficits. These are two core symptoms of autism, which are linked to poorer sleep quality.
- There are a few rare genetic mutations on Dopamine related genes that cause autism.
- Some studies have linked sleep deprivation to reduce Dopamine in the ventral tegmental area. Subsequently, this may be related to the adverse behavioral effects of sleep deprivation.
- Serotonin is involved in avoidance behavior. It’s enriched in a variety of inhibitory brain pathways. It’s also thought to be the “happy” neurotransmitter and is associated with feelings of joy.
- Serotonin levels have been associated with neuroticism, agreeableness, and conscientiousness.
- Recent studies have found various serotonin deficits in people with autism. Serotonin therapies are now being considered as pharmacological interventions.
- Serotonin also has a role in the sleep-wake cycle. This role is complex and is still debated by neuroscientists. Some believe Serotonin keeps us asleep. However, other studies suggest Serotonin helps us to wake up. None-the-less, the consensus is that disruption to Serotonin can disrupt sleep.
Additional studies have highlighted the importance of acetylcholine in sleep and personality. Neurons that use acetylcholine are part of the ‘cholinergic’ system. This system has been implicated in regulating motivation and emotion. Recent research suggests that this system is involved in mediating the effects of sleep on emotion and behavior.
Many imaging studies have correlated brain composition with personality. Here’s a brief rundown of the main findings to date:
- Extraversion is associated with an increased size of the medial orbitofrontal cortex. The orbitofrontal cortex is associated with reward processing.
- The volume of the lateral prefrontal cortex is linked with conscientiousness. This finding makes sense since the region is involved in planning and behavioral control.
- Agreeableness is associated with an increased volume of brain networks involved in the “theory of mind.” Theory of mind allows us to predict and understand the behavior and intentions of others. People with autism can have significant deficits in these skills.
- One study highlighted that white matter is increased in fear and reward networks. These networks include the amygdala and prefrontal cortex. White matter is composed of fatty tissue. This tissue acts as a conductor for electrical impulses between neurons. The fatty substance insulates the pieces of machinery that neurons use to communicate (axons). This fatty substance increases the speed of electrical flow. Hence, a higher level of white matter may suggest hyperactive fear circuits. Hyperactivity of fear-related circuits may explain some of the key traits of neuroticism.
How does personality impact sleep? 🧠
Sleep and personality are both individuals’ predictors of health. But, these two factors are interlinked. The relationship appears to be two-way.
Some personality traits have been associated with sleep health. A 2014 study found that various interesting links between personality traits and sleep:
- People with poor sleep hygiene tend to be low in conscientiousness and agreeableness but high in neuroticism.
- Poor sleep quality is linked with low conscientiousness and high neuroticism.
- Neuroticism is the strongest predictor of sleep quality. Many other studies have reported this finding.
- Low extraversion and conscientiousness also predict sleep quality.
- Personalities that are more dependable and sociable tend do experience less daytime sleepiness. This suggests high scores on traits related to extraversion and conscientiousness are related.
The above results are very robust. Moreover, they have been replicated many times by different researchers. An impressive large-scale analysis of over 22,000 adults has replicated these results.
Does sleep disruption change personality?
Sleep deprivation can have substantial negative consequences. These include suppression of the immune system, heightened anxiety, and reduced cardiovascular health.
In terms of the brain, consistently losing sleep can impair a critical night-time process. For example, a lack of sleep can prevent toxins removal from the brain. It can also impair memory storage and reduce daytime attention. Even losing one hour of sleep per night can contribute to these effects.
The way we behave and perceive the world can also be changed by sleep deprivation. A lack of sleep can impact our personality.
We’re more likely to view ambiguous faces as threatening or harmful when we’ve had a night of disrupted sleep. Sleep deprivation reduces our ability to regulate and understand emotions.
For people with autism, this can be particularly harmful. Autism patients often struggle with these actions as part of their condition. Any further disruption may cause unnecessary feelings of sadness and aggression.
Sleep deprivation is also linked to an increase in risk-taking behavior. This suggests that sleep disruption can reduce conscientiousness. This will affect self-discipline, orderliness, and the ability to plan.
Research has also highlighted increased irritability as a result of disrupted sleep. Over the long-term, this can remove feelings of empathy and care for others. Mapped on to the big five, this looks like a reduction in agreeableness.
It also likely contributes to lower openness scores. This means sleep loss can make people with and without autism less open to new experiences. In terms of autism, sleep deprivation may also further impair social interaction abilities.
Long-term sustained sleep deprivation makes us prone to depression, anxiety, and mood disorders. There are also some concerning biological consequences of sleep deprivation.
A 2010 study demonstrated that long-term sleep deprivation caused the loss of neurons in children. In adults, the loss of sleep can actually ‘shrink’ brain regions over the long-term. This can have a significant impact on cognitive ability. Long-term sleep loss is linked with dementia and cognitive decline in older adults.
Personality and sleep problems in autism 👪
Just like everyone else, people with autism have unique personalities. But, because of their condition, they may be more likely to score highly in some traits. Many studies have investigated this.
A 2015 study compared self-reported personality tests between adults, adolescents, and children with autism to matched controls. The study found the individuals with autism score more highly on neuroticism. People with autism were less extraverted, agreeable, conscientious, and open to the experience.
However, these differences weren’t always substantial. The difference also did not seem the predict the severity of symptoms. This suggests that autism-related behaviors rely on complex non-personality-based mechanisms. Other studies have replicated some of these findings. Many researchers have reported reduced extroversion in children with autism.
One of the big problems faced by people with autism is a disruption to sleep. Many patients experience insomnia and other difficulties in sleeping. We already know how important sleep is to our daily function. We’ve also discussed the interesting two-way relationship between sleep and personality.
Understanding this relationship is very important to autism. Some altered personality traits may contribute to sleeping problems in autism.
A positive (harmful) feedback loop may also exist – click here for the definition.
Sleep disruption can heighten some damaging aspects of personality. Hence, some pre-existing personality traits may become enhanced. This may cause a vicious cycle in patients with autism.
For example, there are indications that neuroticism impairs sleep quality. In parallel, disrupted sleep also seems to infer higher levels of neuroticism. Neuroticism already appears to be higher in some people with autism. So this may turn in to a vicious cycle. This underlines the importance of resolve sleep disruption in people with autism.
Ashleigh Willis is a final year Ph.D. candidate in Neuroscience at the University of Glasgow. Her research investigates the genetic and environmental contributors to mental health and neurodevelopmental conditions. Ashleigh has built research collaborations with McGill University and received specialist training at the Centre for Neuroscience at Montreal General Hospital, McGill University Health Centre. She is also an active member of the Society for Neuroscience. Ashleigh holds an Honours in Psychology, an MRes in Neuroscience, and is fascinated by the neuronal circuits which make us who we are. Ashleigh is passionate about providing a deeper understanding of mental health conditions and sharing an accurate and de-stigmatizing message through talks for organizations such as TEDx, Pint of Science, and the Scottish Funding Council.
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