Motivation and emotion/Book/2018/Natural euphoria
How can euphoria be induced without drugs?
Overview[edit | edit source]
Euphoria affects the body psychologically and physiologically,the pleasurable sensation of euphoria can be induced in various ways, such as romantic love, music, video games and exercise. The problematics surrounding the pleasurable feeling of euphoria is the addictive nature. Literature discussing chemically-induced euphoria such as stimulants or depressants has an over representation surrounding the issue. The brains pleasure centres have a similar reaction whether euphoria is induced naturally or chemically . Studies on excessive exercise or excessive video game play found the brains pleasure centres produced chemicals within the body such as endogenous opioids, endocannabinoid and Beta-endorphin, the release of these chemicals throughout the body can have positive or negative effects psychologically and physiologically. For example, a positive effect is psychological well-being, a negative effect is the physiological dependence or addiction to the production of such chemicals within the body. This book chapter will discuss the brains pleasure centres and how various activities can naturally induce feelings of euphoria.
Euphoria[edit | edit source]
Euphoria can be defined as a state of intense excitement and pleasurable feelings or happiness, well-being, and optimism. Euphoria can be described as symptomatic of a mental illness or the influence of drugs, euphoria activates the brain's reward system. The word "euphoria" is derived from the Ancient Greek terms εὐφορία: εὖ eu meaning "well" and φέρω pherō meaning "to bear". It is semantically opposite to dysphoria. Natural rewards and social activities have been known to induce a state of euphoria. The different types of naturally occurring euphoric stimuli are; exercise, music, sexual intercourse and video games, euphoria can also be induced chemically as a result of stimulants or depressants.
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Reward systems[edit | edit source]
The reward system can be defined as any stimulus activity, object, event or situation that has the potential to make us approach or consume it (Schultz, 2015). Pleasure systems in the brain produce neural structures responsible for incentive salience, for example, motivation or wanting to receive a reward. Pleasure is a core component for the experience of euphoria and happiness (Schultz, 2015). Rewarding stimulus produce attractive and motivational properties that induce appetitive behaviours, approach behaviour and consummatory behaviour (Schultz, 2015). Positive reinforces have been found to be rewarding and play a role in operate conditioning, for example, rewarding stimuli function as positive reinforces (Schultz, 2015). Studies of the reward system have identified three reward states, the first, primary rewards which facilitate the survival of one’s self and offspring. The second, intrinsic rewards are unconditioned rewards that involve attractive and motivational behaviour producing pleasure or euphoria. Finally, extrinsic rewards are conditioned rewards that involve attractive and motivational behaviour, however, extrinsic rewards are not consistent in the production of pleasurable feelings or euphoria (Malenka, Nestler and Hyman, 2009; Nestler, 2013; Schultz, 2015). Research suggests the combination of intrinsic and extrinsic rewards influence the behaviour necessary to maximize pleasurable feelings of euphoria. For example, extrinsic rewards such as money or your favourite sports team winning can elicit euphoric pleasure. Extrinsic rewards develop their motivational value as a result of learned association and conditioning with intrinsic rewards (Malenka, Nestler and Hyman, 2009; Nestler, 2013; Schultz, 2015).
Multiple brain structures are combined to produce a functional reward system (Yager, Garcia, Wunsch and Ferguson, 2015). Within the cortico-basl ganglia-thalamo-cortical loop, the basal ganglia portion of the loop drives activity within the reward system (Yager, Garcia, Wunsch and Ferguson, 2015) . Glutamatergic interneurons link the structures within the reward system (Yager, Garcia, Wunsch and Ferguson, 2015). Dopaminergic projections are sets of neurons that synthesize and release the neurotransmitter dopamine to communicate with other neurons (Yager, Garcia, Wunsch and Ferguson, 2015). Axons run the full length of the dopamine neuron pathways, the neurons’ somata produce the enzymes that synthesize dopamine neurons (Yager, Garcia, Wunsch and Ferguson, 2015). Dopamine pathways within the ventral tegmental area are also part of the reward system, these dopamine pathways can stimulate or inhibit D1-like receptors or D2- like receptors (Malenka, Nestler and Hyman, 2009; Nestler, 2013; Schultz, 2015).
The reward system contains Hedonic hotspot that are functionally linked between different brain structures that facilitate pleasure, the activation of one hedonic hotspot results in the recruitment of the others (Berridge & Kringelbach 2015; Pecina, Smith and Berridge, 2006). There are three psychological components for mapping pleasure in the brain (Berridge & Kringelbach 2015). The first psychological component is liking - a core reaction to hedonic impact. The second psychological component is wanting - a motivation process of incentive salience. The third psychological component is learning - a Pavlovian or instrumental associations and cognitive representations. Functional magnetic resonance imaging (fMRI) have revealed that the inhibition of one hotspot results in blunting the activation of another hotspot. This simultaneous activation of every hedonic hotspot within the reward system is believed to be necessary for generating the sensation of intense euphoria (Berridge & Kringelbach 2015). Neuroscientists using fMRI have identified hedonic hotspots in sub-compartments within the nucleus accumbens shell, ventral pallidum, parabrachial nucleus, orbitofrontal cortex, and insular cortex. There are three main regions within the brain associated with pleasure; the ventral pallidum (pleasure does not occur without it), the nucleus accumbens (pleasure occurs when activated) and the orbitofrontal cortex (its activation correlates with pleasure) (Berridge & Kringelbach 2015).
Romantic love-induced euphoria[edit | edit source]
Romantic love or Copulation is a biological instinct within all people, the need to reproduce is a primitive drive that motivates individuals to seek out a mate. Vroom’s Expectancy Theory is founded on the basic notions of effort, performance, and reward (Parijat & Bagga, 2014). The key constructs to the expectancy theory of motivation are; Valence, Expectancy, and Instrumentality. Valence - is the value or the strength an individual places on a particular outcome/reward, for example, the need to reproduce is of value to the individuals survival, the strength is driven by the biological instinct to reproduce. Expectancy - relates effort to performance, for example, how much effort an individual puts into seek out a mate (social or financial status). Instrumentality - is the belief that performance is related to rewards, for example, in contemporary society individual performance such as monetary gain, materialistic value or “peacocking” individual financial success and social class, this increases the potential of finding a suitable mate to reproduce with (Parijat & Bagga, 2014).
Romantic love involves four components; cognitive, erotic, behavioural and emotional (Emanuele, Politi, Bianchi, Minoretti, Bertona and Geroldi, 2005). The early stages stimulate intense emotional and motivational responses such as euphoria, focused attention, and obsessive thinking (Aron, Fisher, Mashek, Strong, Li and Brown, 2005; Emanuele et al., 2005). Researchers suggest emotional responses such as euphoria and focused attention involve reward and motivational systems in the brain (Aron et al., 2005; Emanuele et al., 2005). Studies using MRI and fMRI revealed multiple brain structures are involved in producing the feelings of romantic love or euphoria .
The brain structures involved are located in the cortex region, the medial insula, anterior cingulate and the hippocampus (Zeki, 2007). The subcortical regions that mediate reward such as nucleus accumbens and ventral tegmental area are also involved in the production of feelings of euphoria (Aron et al., 2005). Romantic love is a goal directed behaviour that incorporates various emotions, the biochemical mechanisms effect changes in mood (Zeki, 2007; Emanuele et al., 2005). Emanuele et al., (2005) concluded the levels of neurotrophins increase, for example, plasma levels of NGF in the bloodstream, suggesting the increased levels could be related to specific emotions such as euphoria.
Romantic love creates feelings of exhilaration and euphoria cocaine or heroin act on humans to produce euphoria or addiction. The cortex and subcortical are flooded with high concentrations of neuro-modulators such as dopamine which is associated with reward and euphoria. Oxytocin and vasopressin are two other neuro-modulators linked to romantic love (Zeki, 2007). The dopamine release by the hypothalamus functions as a link between the nervous and the endocrine systems these are the same regions that become active when exogenous opiate drugs are introduced to the system causing euphoria. The dopamine release by the hypothalamus creates a decrease in serotonin (5-hydroxytryptamine) to levels that are common in people with obsessive-compulsive disorder suggesting the increase - decrease of neuro-modulators is linked to the obsession part of romantic love (Zeki, 2007). Oxytocin and vasopressin are both produced by the hypothalamus and are linked to attachment and bonding, they are stored and released in the pituitary gland then discharged into the blood during orgasm (Zeki, 2007).the same circuity that drugs such as
Music-induced euphoria[edit | edit source]
Certain stimuli has the potential to produce intense feelings of pleasure,biological reinforces, synthetic chemicals, or tangible items referred to as secondary rewards (Salimpoor, Benovoy, Larcher, Dagher & Zatorre, 2011, p. 257). Exposure to certain stimuli such as music, has been known to stimulate dopaminergic activity in the mesolimbic system (Salimpoor et al., 2011). Blood & Zatorre (2011) found there is a correlation between pleasurable responses to music and feeling of euphoria. Researchers have observed an increase in cerebral blood flow in multiple brain structures involving the reward system (Blood & Zatorre, 2011). The brain structures activated when listening to music stimulate the ventral striatum, mid-brain, amygdala, orbito-frontal cortex and ventral medial prefrontal cortex that produce the pleasurable feelings of euphoria (Blood & Zatorre, 2011). The activity observed within these brain structures is known to involve dopamine and opioid systems. Salimpoor et al., (2011) found listening to music induced an emotional arousal that stimulated a release of endogenous dopamine into the striatum.these rewarding stimuli are either
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Video-game-induced euphoria[edit | edit source]
The millennial generation has become somewhat hypnotizeswith video games online and handheld mobile devices the increased screen time has become the latest phenomena. Parents are concerned with their children's physical and psychological health and well-being (King & Delfabbro, 2009; Lemmens, Valkenburg and Peter, 2009). Parents and caregivers are concerned about video game addiction or dependence, many children are displaying alarming behavioural changes such as physical violence, lateral violence, and disengagement impacting their home and school life (King & Delfabbro, 2009). Children are spending more time playing video games then playing outside or doing their homework and chores (Griffiths & Hunt 1998). The severity of the situation is children no longer want, they need to play video games. The need to play video games becomes so overwhelming children neglect the fundamental pleasures of life to chase the euphoric feelings they receive from playing video games. The approach-avoidance behaviour replaces fundamental pleasures with higher order pleasures such as video games becomes the new driving motivation for gamers (Corr, 2013; Griffiths & Hunt 1998). Gamers are people who plays online video games (Griffiths & Hunt 1998). Studies have found people who play video games experience pleasurable feelings or euphoria, however, many researchers are concerned about the long-term effects of exposure to video games has on the individual (Griffiths & Hunt 1998; King & Delfabbro, 2009). One of the controversial concerns is addiction or dependence, many studies have revealed the potential for pathological health implications from the long-term exposure to video games. One explanation for the motivation for the excessive game play is Need Theory (McClelland, 1987). People who acquire a particular need behave differently from those who do not have that need, for example, the kinds of events people experience in the environment and culture (McClelland, 1987; Conger & Kanungo, 1988). McClelland’s Need Theory focuses on three needs; Achievement, Power and Affiliation (McClelland, 1987; Conger & Kanungo, 1988).
- The game rewards
- Reward delivery in relation to player
- Achievement points are similar to loyalty reward programs they reward players for completing the game or playing a game nonstop for hours, for example, playing for eight hours straight.
- Rewards in video games are particularly salient to males
- The rewards in video games are often the primary motivation for playing
- Complex reward structures that require multitasking management skills and a great deal of player concentration
- Empowerment refers to the highlighted sense of power or authority
- Experience of feeling a sense of mastery over the virtual properties of the video game
- Status or rank
- Control and recognition
- Strong sense of personal agency within the game content
- Manipulate and interact with features of video game environment
- A sense of personal freedom is being able to choose how the video game stories will be resolved or controlling the outcome in the game events using personal strategy
- The role of social networks and social responsibilities in games
- Players could compare their progress in the video game with their friends or other players
- Social networks have been associated with social responsibilities, a social responsibility for each play within the network as they are part of a playing group and they rely on each other
- A type of online community which shares a common space, common experiences with friends in the game
Children playing video games are motivated by the virtual reward frequency (variable ratio reinforcement schedules) and the structural characteristics within the video games. The video game engineers have used multiple strategies to keep gamer's dependent or addicted to the video game, similar strategies that are used for poker machines (King & Delfabbro, 2009). Research suggests prolonged exposure or excessive use of video games can lead to behavioural addictions such as compulsive, uncontrollable and psychologically or physically destructive behaviour (Lemmens, Valkenburg and Peter, 2009; Griffiths & Hunt 1998). Studies investigating the problematic use of video games have used the American Psychiatric Association diagnosis for pathological gambling as the criteria for diagnosing dependent or addicted online gamer's (Lemmens, Valkenburg and Peter, 2009; Griffiths & Hunt, 1998; King & Delfabbro, 2009).
The addiction criteria model:
- The excessive game play dominates the Gamer's feelings, thinking and behaviour.
- Gamer's begin playing video games more often, gradually building up the amount of time spent on playing video games.
- Gamer's increasingly chase the 'high' or euphoria they experience from playing video games.
- The unpleasant emotions or physical side effects that occur when the gamer discontinues or reduces time spent from video games.
- The tendency to revert back to earlier excessive patterns of game play.
- The interpersonal conflict resulting from excessive gaming, also the conflict between the gamer and those around them.
- Problems caused from excessive game play, displacement problems is the object of addiction, gaming takes preference over essential life activities, such as school work and family commitments ultimately causing psychiatric conflict and/or subjective feelings of loss of control.
Exercise-induced euphoria[edit | edit source]
Endorphins are endogenous opioids that are released from the pituitary gland, endogenous opioids mediate analgesia or euphoria and play a role in the brains reward system (Leuenberger, 2006). Research suggests that endorphins are responsible for creating the psychological state known as "runners' high". The endogenous opioid system is closely linked to different neurotransmitter systems within the brain such as dopaminergic, noradrenergic, serotonergic, GABA-ergic and glutamatergic systems (Leuenberger, 2006). The endorphin hypothesis proposes that the effects of acute exercise is beneficial for psychological and physiological well-being, for example, the positive effects of euphoria. Euphoria is caused by the release of endogenous opioids, for example, β-endorphin receptor sites within the brain (Leuenberger, 2006). Research suggests that physical activity is associated with positive mood and improves emotional well-being (Daley, 2002; Buckly, 2018). Daley (2002) concluded that physical exercise reduces depression and anxiety, there is supporting evidence that a positive relationship between exercise as a therapy for treating mental illness (Daley, 2002; Buckly, 2018). Studies have also found positive effect in relation to exercise on both the serum and cerebrospinal fluid concentrations of endocannabinoids (Dietrich & McDaniel, 2004; Daley, 2002; Buckly, 2018). The presence of cannabinoid receptors in the muscle, skin, endothelial cells and lungs suggest a possible role for the endocannabinoid system in mediating certain physiological responses to exercise (Dietrich & McDaniel 2004). Prior to the discovery of endogenous opioid system, researchers tried to account for the analgesic and euphoric states with alterations in the catecholamine adrenaline (epinephrine) and noradrenaline (norepinephrine) (Dietrich & McDaniel, 2004; Daley, 2002; Buckly, 2018).
Literature defines the runners' high as feelings of happiness, harmony, boundless energy and at peace with oneself. Research found the runners' high reduced the physical sensation of pain, however, the runners' high is not experienced by all runners (Sher, 1998). Studies found the runners' high does not occur consistently in all runners even if an individual has experienced it previously beforeBeta-endorphins are increased during and after physical activity, high intensity exercise can stimulate the release of Beta-endorphins into the blood circulation (Sher, 1998). Research suggest the endogenous euphoric reward is responsible for the reinforcement of physical training and the changes in psychological functions as a direct consequence of alterations in endogenous opioid release (Sher, 1998).. Research suggests that plasma levels or
Exercise dependence is not currently recognized by the DSM-V. Studies suggest the µ-opiate receptor is involved in the development of exercise dependence, furthermore, the endogenous opioid system is a key factor for generating addictions (Johnston, Reilly and Kremer, 2011). The endogenous opiate system stimulates dopamine release in the nucleus accumbens,this suggests the endogenous opiate system influences addiction. The endogenous opiates act directly in the nucleus accumbens (Allegre, Souville, Therme and Griffiths, 2006). Studies suggest dopamine as the major component within the process of addictions. Individuals labelled as exercise dependent show similar behaviours and hormone levels to those of alcoholism and drug addicts. Researchers have found two neurotransmitter systems that correlate with addiction or dependence, the dopaminergic and the opioidergic systems. The ventral tegmental area and the nucleus accumbens are two of the brains regions that are involved in reward circuit of the central nervous system, collectively they form the mesolimbic dopamine system (Johnston, Reilly and Kremer, 2011). Groups of cells in the ventral tegmental area synapse in the nucleus accumbens and release dopamine. Studies suggest that exercise dependence is increasing and needs to be recognized within the DSM-V (Allegre, Souville, Therme and Griffiths, 2006).
Conclusion[edit | edit source]
In conclusion, euphoria whether being naturally or chemically induced, can have problems with addiction or dependence. Literature surrounding the issue highlights the positive or negative effects of euphoria. This book chapter has looked at the brainspleasure centres and the similar reaction naturally or chemically induced euphoria has on the body and mind . The main highlights presented within this chapter focused on the various ways euphoria can be naturally induced, such as the experience of romantic love, listening to music, playing video games and exercise. More research needs to be conducted into the pros and cons of euphoria as much of the literature focuses more on chemically induced euphoric states rather than the naturally induced euphoric states.
See also[edit | edit source]
- Emotion (Wikipedia)
- Endorphins and motivation (Book chapter, 2018)
- Euphoria (Wikipedia)
- Euphoria as an emotion (Book chapter, 2016)
- Exercise types and emotion (Book chapter, 2018)
- Mystical experiences and emotion (Book chapter, 2018)
References[edit | edit source]
Aron, A., Fisher, H., Mashek, D. J., Strong, G., Haifang, L., & Brown, L. L. (2005). Reward, motivation and emotion systems associated with early-stage intense romantic love. The American Physiological Society, 94, 327-337. doi:10.1152/jn.00838.2004
Berridge, K. C., & Kringelbach, M. L. (2015). Pleasure systems in the brain. Neuron Review, 86, 646-664. Retrieved from http://dx.doi.org/10.1016/j.neuron.2015.02.018
Blood, A. J., & Zatorre, R. J. (2001). Intensely pleasurable responses to music correlate with activity in brain regions implicated in reward and emotion. PNAS, 98(20), 11818-11823. doi:10.1073/pnas.191355898
Buckly, R. (2018). Nature sports, health and ageing: the value of euphoria. Annals of Leisure Research, 1-17. doi:10.1080/11745398.2018.1483734
Conger, J. A., & Kanungo, R. N. (1988). The empowerment process: Integrating theory and practice. Academy of Management Review, 13(3), 471-482. Retrieved from https://doi.org/10.5465/amr.1988.4306983
Corr, P. J. (2013). Approach and avoidance behavior: multiple systems and their interactions. Emotion review, 5(3), 285-290.
Daley, A. J. (2002). Exercise therapy and mental health in clinical populations: is exercise therapy a worthwhile intervention? Advances in Psychiatric Treatment, 8, 262-270. doi:10.1192/apt.8.4.262
Dietrich, A., & McDaniel, W. F. (2004). Endocannabinoids and exercise. Br J Sports Med, 38, 536-541. doi:10.1136/bjsm
Emanuele, E., Politi, P., Bianchi, M., Minoretti, P., Bertona, M., & Geroldi, D. (2005). Raised plasma nerve growth factor levels associated with early-stage romantic love. Psychoneuroendocrinology, 31, 228- 294. doi:10.1016/j.psyneuen.2005.09.002
Griffiths, M. (1997). Exercise addiction: A case study. Addiction Research, 5(2), 161-168. Retrieved from https://doi.org/10.3109/16066359709005257
Griffiths, M. D., & Hunt, N. (1998). Dependence on computer games by adolescents. Psychological Reports, 82, 475- 480. Retrieved from https://doi.org/10.2466%2Fpr0.1918.104.22.1685
Johnston, O., Reilly, J., & Kremer, J. (2011). Excessive exercise: from quantitative categorization to a qualitative continuum approach. Eating Disorders Association, 19, 237-248. doi:10.1002/erv.970
Kelley, H. H., & Michela, J. L. (1980). Attribution theory and research. Annual Reviews, 31, 457-501.
King, D., & Delfabbro, P. (2009). Understanding and assisting excessive players of video games: a community psychology perspective. The Australian Community Psychiatrist, 21(1), 62- 74. Retrieved from https://www.researchgate.net/profile/Daniel_King6/publication/284503482_Understanding_and_Assisting_Excessive_Players_of_Video_Games_A_Community_Psychology_Perspective/links/02e7e526d79ecb59d9000000/Understanding-and-Assisting-Excessive-Players-of-Video-Games-A-Community-Psychology-Perspective.pdf
Lemmens, J. S., Valkenbenberg, P. M., & Peter, J. (2009). Development and validation of a game addiction scale for adolescents. Media psychology, 12, 77- 95. Retrieved from https://doi.org/10.1080/15213260802669458
Leuenberger, A. (2006). Endorphins, exercise, and addictions: A review of exercise dependence. Impulse: the premier Journal for undergraduate publications in the neurosciences, 1-9. Retrieved from https://impulse.appstate.edu/sites/impulse.appstate.edu/files/2006_06_05_Leuenberger.pdf
Malenka, R. C., Nestler, E. J., & Hyman, S. E. (2009). Excitatory and inhibitory amino acids. Molecular Neuropharmacology: A Foundation for Clinical Neuroscience, 191-368. Retrieved from https://www.scirp.org/(S(lz5mqp453edsnp55rrgjct55))/reference/ReferencesPapers.aspx?ReferenceID=2074120
McClelland, D. C. (1987). Human motivation. Cambridge University press, 1-288. Retrieved from https://books.google.com.au/books?hl=en&lr=&id=vic4AAAAIAAJ&oi=fnd&pg=PR3&dq=mcclelland%27s+need+theory+of+motivation+&ots=As_R9IV0b5&sig=Gn23QJh3RcCTt1vlJVnBMLBhFKA#v=onepage&q=mcclelland's%20need%20theory%20of%20motivation&f=false
Nestler, E. J. (2013). Cellular basis of memory for addiction. Dialogues in Clinical Neuroscience, 15(4), 431-443. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898681/
Nichols, D. S., & Glenn, T. M. (1994). Effects of aerobic exercise on pain perception, affect, and level of disability in individuals with fibromyalgia. Journal of the American Physical Therapy Association, 74(4), 327-332.
Oh, A., & Yi, E. (2017). A study on the effects of exercise motivation of the elderly people on euphoria. Journal of Exercise Rehabilitation, 13(4), 387-392. Retrieved from https://doi.org/10.12965/jer.1735084.542
Parijat, P., & Bagga, S. (2014). Victor vroom's expectancy theory of motivation – An evaluation. International Research Journal of Business and Management, 7(9), 1-8. Retrieved from http://irjbm.org/irjbm2013/Sep2014/Paper1.pdf
Pecina, S., Smith, K. S., & Berridge, K. C. (2006). Hedonic hotspots in the brain. Department of Psychology, 12(6), 500-511. doi:10.1177/1073858406293154
Salimpoor, V. N., Benovoy, M., Larcher, K., Dagher, A., & Zatorre, R. J. (2011). Automatically distinct dopamine release during anticipation and experience of peak emotion to music. Nature Neuroscience, 14(2), 257-262. doi:10.1038/nn.2726
Schultz, W. (2015). Neuronal reward and decision signals: From theories to data. Physiological Reviews, 95(3), 853-951. doi:10.1152/physrev.00023.2014
Sher, L. (1998). The endogenous euphoric reward system that reinforces physical training: a mechanism for mankind's survival. Medical Hypotheses, 51, 449-450.
Yager, L. M., Garcia, A. F., Wunsch, A. M., & Ferguson, S. M. (2015). The ins and outs of the striatum: Role in drug addiction. Author Manuscript, 301, 529-541. doi:10.1016/j.neuroscience.2015.06.033
Zeki, S. (2007). The neurobiology of love. Federation of European Biochemical Societies, 581, 2575-2579. doi:10.1016/j.febslet.2007.03.094
[edit | edit source]
- A state of euphoria - https://www.youtube.com/watch?v=29J62W8DUho
- Brain mechanisms of pleasure and addiction - https://www.youtube.com/watch?v=de_b7k9kQp0
- Endorphins: The brain's natural morphine - https://www.youtube.com/watch?v=QWcfTGIU2Hs
- EUPHORIA - WikiVidi documentary https://www.youtube.com/watch?v=AEOxA3ps0J4
- Explaining a 'runner's high' - https://www.youtube.com/watch?v=CV-sioJAJQQ
- How to boost your happy chemicals - Dopamine, Oxytocin, Serotonin and Endorphin Hormones - https://www.youtube.com/watch?v=9l4PzhcYQrE
- The feeling of euphoria after running - RUNNER'S HIGH (explained) - https://www.youtube.com/watch?v=69vWrkySCgE
- What causes runner's high? - https://www.youtube.com/watch?v=TElAJMm34IE