Many scientific studies and experimental designs tend to compare the brain's "resting state" to its performance when engaged in an activity. The difference between the two states is often seen as the basis to accept or reject a certain hypothesis. Yet not a lot of studies consider simply the "resting state" itself. Therefore, one could ask the question "What does rest actually mean?"
This literature review is going to investigate research focused on resting and vacationing to address the phenomenon of rest and discover what happens within the brain when somebody's having some time off.
What is rest?
Rest is a phenomenon used by many researchers to describe the default state of mind. Yet, there are few attempts to identify this "blank slate" condition.
In one study, a researcher conducted interviews with 63 participants along with an in-depth literature review of academic literature about the phenomenon of rest (Asp, 2015). They came to several conclusions. First, that most people define rest by its opposite state - non-rest - and the transitions between the two. Second, the researcher identified several properties to further clarify the phenomenon:
rest involves a harmonious alignment of feelings, actions, and motivations, enabling pleasurable activities;
rest occurs when personal needs meet the environment's nature, ranging from peaceful, undemanding states to those receptive to enjoyment;
rest embodies confidence, dignity, and feeling loved.
Some other factors of rest mentioned in academic literature relate to distinguishing it from sleep. Despite sleep being a seemingly obvious form of relaxation, it is not entirely effective to define it in the same way as rest. Due to the complex processes within the sleeping brain the nature of sleep includes several stages and requires considerable amounts of time to go through them. These complications make it challenging for experimental research to view sleep as a state of definitive relaxation of the mind. Research defines resting while awake as an activity involving engagement in personal (i.e. non-work) activities while not thinking about work and overall reducing cognitive demands (Eccles et al., 2023).
However, a rigorous reader might ask the question "Well, what about travelling and active vacationing?". These activities do fall within the scope of our definition of rest. In fact, it is suggested that going away for a holiday can yield more beneficial results than simply staying in after work (de Bloom et al., 2017). For example, one study investigated workers' behavioural, cognitive, and emotional states during vacations and while staying at home during their time off. The study confirmed that the physical distance from home and work when travelling stimulates resource-providing behaviour and detaches one from work routines. At-home leisure comparatively induced ruminative thinking, reduced socialisation, and included the need for obligatory activities such as house chores (de Bloom et al., 2017).
Therefore, based on academic research, the phenomenon of "rest" can be defined as a state of mind which includes reduced cognitive demands, separation from daily chores and activities, increased socialisation and novel experiences, and compatibility between the environment and inner needs of a person.
How does rest work?
Despite the phenomenon of vacationing being well-explained in studies related to the tourism industry, its definition for experimental psychological studies is not that intricately identified.
In fact, until recently, most fMRI studies focused on imaging of the brain while engaged in certain activities, such as counting, imagining, recall, etc. Yet, in the 1990s - by a happy accident - a neurologist Marcus Raichle discovered an unknown area of study. He noticed that in experiments where the participants were asked to rest before performing a task, their brains were not completely shut down. After preforming several research projects exploring the resting brain, Professor Raichle was awarded the Kavil Prize in Neuroscience.
His most influential work investigates the "default brain function" which had been used as a control state by many scientists in their research, despite not being definitively defined. The study was conducted via a between-subjects experiment which obtained brain scans in two resting conditions - with subject’s eyes closed and with subject’s eyes open viewing a provided visual fixation (Raichle, 2001). The results showed that several distinct areas were activated in resting state:
areas in the right gyrus rectus (BA 11);
visual areas of the occipital lobe (BA 17, 18, 19, 37);
visual areas in the parietal lobe (BA 7, 31).
These results were obtained by measuring the Oxygen Extraction Fraction (OEF) in three groups of participants.
PET scanning methods calculate the blood flow in the brain. In areas where there was increased activity, the blood flow does too. However, it has also been discovered that the increase and decrease of blood flow is accompanied by less noticeable changes in oxygen consumption: when the blood flow increases, less oxygen is being extracted from it, and vice versa. (Raichle, 2001)
How to rest effectively?
From Raichle's study, the popular ways to rest can be identified due to their connection to certain brain areas.
Brodmann's Area 11
Brodmann Area 11 is responsible for processing emotion and value (Ueda et al., 2017). For example, when you are given a choice of either eating a dragonfly for a thousand dollars or cleaning up a smelly pile of rubbish for ten, it is likely that you will choose the first option due to the increased reward (Rogers et al., 1999).
In terms of rest, a wonderful way to stimulate this part of your brain would be doing something unusual - such as going on a high-peak holiday or, if you're feeling less energetic, going on a walk at a time of day when you usually do not. Since visual cortices are also involved in resting state, it would also be beneficial to take a note of unfamiliar things in your environment to stimulate this brain area.
Moreover, the disconnection from work and daily routine mentioned above as a part of the definition of rest is likely to occur when obtaining new experiences - whether it's skydiving or a simple walk in a new part of the neighbourhood.
Brodmann's Areas 17, 18, 19
Brodmann Areas 17, 18, and 19 are all defined as the visual cortices of the occipital lobe, with BA 17 being recognised as the primary visual cortex (Kawachi, 2017). It has also been discovered that each of these three areas has its own smaller part in connection to other regions of the brain (Morrison et al., 1998). These areas play a pivotal role in recognition of light intensity, detection of patters, colour recognition, and movement tracking (Silva et al., 2018). These areas operate no matter what - when you are taking a stroll, enjoying the sunset, or watching a movie.
It is likely that this area stays activated in resting state to visually detect changes in the environment and? respond to them if needed. One of the ways to use this to relax is to ensure that your surroundings are as comfortable as possible and focus on one particular thing. For instance, if you are fascinated by dinosaurs or love outer space, it would be a great idea to go to a museum. This would ensure a pleasant experience, while the visual cortex would be primarily engaged in obtaining and processing the information that keeps you entertained.
Brodmann's Area 37
Otherwise known as the posterior and inferior temporal cortex, Brodmann's area 37 is mainly responsible for face recognition and naming of objects (Thangavel et al., 2008). For example, in normal aging this area remains seemingly unaffected, while in Alzheimer's Disease patients the distribution of neurofibrillary tangles (NFTs) in BA37 becomes patchy, causing difficulties with naming objects and recognising faces.
When you are intending to relax, it would be fitting to think about hanging out with your friends and family. Being surrounded by familiar faces will not only stimulate BA 37, but also create a sense of safety. This ensures that the visual areas mentioned above are not overly engaged in tracking potential hazards but are focused in taking in the present experience instead.
Brodmann's Area 31
Brodmann's area 31 is defined as the dorsal part of the posterior cingulate cortex (dPCC). It plays a key role in motor functions such as body orientation and processing visuospatial information like object movement, change of emotion, and social interactions (Baker et al., 2018). For example, this brain area activates every time you engage in small talk in an elevator. It recognises not only the emotions of the person you are talking to, but also the moment you need to get out of the elevator on the right floor.
As opposed to things you could do to stimulate BA 37, in case of BA 31 it could be nice to meet some new people. What was the last time you went to a club or a pub with some friends? Maybe your time off is just right to do something like this - and bring your friends along! Not only will you have a wonderful time with people you know, but this will also tickle your brain in all the right ways.
Brodmann's Area 7
The The final part of the brain engaged in resting state is Brodmann's Area 7. It is responsible for coordinating motor movements, especially when what you are doing requires reaching, grasping, and coordination of both hands' movements (Le et al., 2017). Many popular hobbies require the engagement of this zone, be it knitting or playing squash.
To relax, it would be beneficial to try a new hobby, such as pottery or painting, which needs a lot of concentration and motor skills. Moreover, most sports require extreme levels of coordination, so if you're feeling energetic - think about going to the nearest basketball field and scoring a couple points!
Some extra advice to make your rest more effective
Food for thought - how to properly feed your brain
Even though the phenomenon of rest has now been relatively well-defined, it is still crucial to understand that lifestyle choices affect the brain no less than experiences. One of the things you could do to ensure the best results of your time off is reevaluating your diet. Here are some of the things to consider:
Antioxidants
One of the main resources consumed by the brain is oxygen. Even though consumption fraction (OCF) decreases due to a rise in blood flow in active brain areas, it is important to ensure that the amount of oxygen in your blood is high enough (Raichle, 2001). [HB1] Moreover, oxygen consumption creates free radicals which tend to damage healthy cells. Therefore, including foods rich in antioxidants would ensure healthy oxygen levels within the blood flow while at the same time reducing the side-effect of oxidation.
Some of the foods known for their high contents of antioxidants are leafy greens such as kale, spinach, or lettuce, as well as some starchy vegetables like potatoes and squash (Ellis, 2021). Also be on the lookout for foods rich in vitamins E, C, and carotenoids - well-known antioxidants.
Omega-3 Fatty Acids
Omega-3 fatty acids are one of the most important drivers of lipid transformation in mammals. These fatty acids are known to increase blood flow in the brain as well as help form molecules that help reduce inflammation (Dighriri et al., 2022; Lemoine et al., 2020). A systematic review of studies investigating the effect of Omega-3 on brain function confirmed its beneficial effects on learning, memory, and overall cognitive well-being (Dighriri et al., 2022). However, it is important to know about Omega-3's "evil sister" - Omega-6. This is a fatty acid that is said to be harmless in moderation yet possesses some pro-inflammatory processes when not balanced out by Omega-3.
Various kinds of Omega-3 can be found in fish oils and in seed oils such as flax or canola oils (National Institutes of Health, 2022). Omega-6, which should be consumed in moderation, is found in rice, eggs, and deep-fried foods (WebMD, 2022).
Caffeine
Caffeine is said to be the worlds most consumed drug. Academic studies show mixed effects on brain function. The three main mechanisms of caffeine in human body are, first, the binding of adenosine decreasing its depressing effects, second, the mobilisation of intercellular calcium increasing mental agility, and third, the inhibition of phosphodiesterase, stimulating the release of dopamine . Caffeine is believed to act as a stimulator of long- and short-term memory, especially during recall and an enhancer of processing speed. But, when consumed in large amounts, caffeine can cause anxiety (Fiani, 2021). Therefore, caffeine can be a nice little brain treat, but, as it happens with things like that, it shouldn't be consumed in large amounts.
Setting boundaries and distancing
When aiming for effective time off, it is important to create a physical distance between yourself and the things that might cause stress, such as work, studies, or annoying daily chores. Researchers suggest that physical distance can encourage socialisation, better sleep, and increased engagement, while at the same time reducing engagement in obligatory activities and ruminative thinking (de Bloom, 2016). Moreover, people who travel during their time off are more likely to engage in resource-producing activities in comparison with resource-consuming activities that are likely to be chosen by those staying at home (de Bloom, 2016).
Conclusion
Despite rest having been used as a controlled state in a plethora of psychological trials, until recently it was not fully identified. Based on the literature review above, it can be said that rest encompasses a specific mindset that is best reached by a coordination between the environment and the needs of an individual. This can include, but are not limited to, reduced cognitive demands, the feeling of being loved, and small stimulations of the resting brain.
As for personal implications, it is for you to decide what you do in your free time. However, judging by the research summarised above, one of the best ways to relax would be spending time with your friends doing something you've never tried before, preferably in a new setting. T his can be accompanied by a nice evening out filled with dining on dishes full of healthy vitamins (did you know that shawarma is extremely healthy food?).
Everybody has their own ways to relax. It is likely that you have already found your most effective ways to rest. Nevertheless, this literature review might help you understand your brain better and learn new ways to give it a treat at the right time.
References
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