May 2021 research roundup: sleeping habits matter

grayscale photo of sleeping woman lying on bed

Human beings perform routine tasks daily. These actions generally include eating, working, sleeping, and the repetition of those daily processes. As we devote plenty of our time to sleeping and eating, they must be extremely important to us. In this research roundup, with the help of recent studies, we will try to shed some light on the effects that sleep and food can have on the performance of day-to-day cognitive tasks. 

Ever wondered why a night of sleeplessness makes you inefficient at work the next day? This study provides some answers. 

Sleep deprivation and insomnia have been long known to affect cognitive performance, motor functions, immune responses, emotional and physical well-being. The ill-effects of sleep deprivation only become prominent after a continuous long time exposure leading to a sleep disorder. However, an important question that needs to be asked is whether a single night of sleep deprivation (short exposure) can affect our body, brain and cognitive functioning. A recent study published in the journal of Biol. Sport tried to investigate the impact of one night of sleep deprivation on cognitive, motor and psychomotor performance. Two groups of 15 participants each participated in the study. Participants of one group were allowed to have a normal night sleep of 8 hours; however, participants of the other group were kept sleep deprived for 24 hours. A battery of psychophysical tests was administered on both of the groups to assess executive functioning (automated neuropsychological assessment test), cognitive performance (Go/No-Go test, Stroop tests), psychomotor performance (speed-accuracy tasks) and motor performance (use of countermovement jump test, handgrip strength test and arm and leg contraction tasks). One night of sleep deprivation led to impairment and a significant decrease in the executive functions but did not affect the psychomotor and motor abilities.

Skurvydas, A. et al. (2020) ‘One night of sleep deprivation impairs executive function but does not affect psychomotor or motor performance’, Biology of Sport, 37(1), pp. 7–14. doi: 10.5114/biolsport.2020.89936.

How does the cognitive ‘day’ profile look like after being subjected to sleep deprivation? 

It is a well-established fact that cognitive and executive functions are impaired followed by a night of sleep deprivation; however, the way the impairment fluctuates through the day remains elusive. A research group from Karolinska Institutet, Stockholm, Sweden, recently published an article in the Frontiers in Behavioural neuroscience wherein they used an innovative approach of using smartphones to collect data for commonly used cognitive tests. A total of 182 participants (divided into two groups of 91 participants each, sleep deprivation group and control group) completed an array of 2-min cognitive tests to measure attention levels, arithmetic ability and episodic and working memory. The subjects’ performance was assessed at different time points in the day (8:00 hrs, 12:30 hrs and 4:30 hrs). The performance levels were then compared with the baseline performance levels recorded on the previous night at 22:30 hours, followed by which sleep schedules were enforced on different participants. Based on the reported data, it can be observed that attention deficits remain similar throughout the day, arithmetic ability was hampered the most during the first half, whereas impairment in the memory component increased as the day progressed with maximum inefficiency in the evenings. Therefore, sleep deprivation in participants showed deficits in all of the above cognitive scales and the performance levels fluctuated randomly as the day progressed.

Holding, B. C. et al. (2021) ‘Quantifying Cognitive Impairment After Sleep Deprivation at Different Times of Day: A Proof of Concept Using Ultra-Short Smartphone-Based Tests’, Frontiers in Behavioral Neuroscience, 15(April). doi: 10.3389/fnbeh.2021.666146.

Do you feel impulsive and disoriented? You may want to check on your diet.

According to a study published in the ‘International Journal of eating disorders’ binge-eating disorders are associated with impulsivity, emotional dysregulation and obesity. Binge-eating disorder is the most common type of eating disorder, which is marked by consuming large amounts of food very quickly and frequently. To dissect the association of binge-eating disorder (BED) and obesity (OB) with executive functioning, a collection of neuropsychological assessment tests were administered on a different group of participants (the first group consists of individuals with BED and OB, the second group with individuals with just OB and the third group with no eating disorders). The neuropsychological tests included assessments for inhibitory control (color-word interference test), sustained attention (D2 concentration endurance test), cognitive flexibility (comprehensive trail making test) and decision making (Iowa gambling task). It was observed that executive functioning was compromised in both groups consisting of individuals with BED + OB and individuals with OB only. These individuals showed more difficulties in inhibitory control (more impulsivity) and displayed lower attention endurance scores. Although the other parameters like cognitive flexibility and decision-making abilities remained unaltered, on summarizing the content of the study, it can be accepted with a high level of confidence that binge eating disorder and obesity adversely affect executive functioning and task performance. 

Kittel, R., Schmidt, R. and Hilbert, A. (2017) ‘Executive functions in adolescents with binge-eating disorder and obesity’, International Journal of Eating Disorders, 50(8), pp. 933–941. doi: 10.1002/eat.22714.

What happens to your brain when you binge eat.

So far, it’s clear from the study above that binge-eating disorders can make us more impulsive, can hamper our attention levels and can also bring in negative effects when it comes to our emotional regulations. As to how we behave is totally dependent upon what happens in our brain, I’ll Watling habits must interfere with the brain’s signaling. A wonderful piece of research published in the journal of Brain sciences found links associating the two things. They used three groups of individuals similar to what was used in the study above. In this study, researchers used a cutting-edge technique known as functional near-infrared spectroscopy to record neural activity patterns from the prefrontal and orbitofrontal cortices while individuals performed a response inhibition task. These two areas of the brain are known to be involved in higher cognitive functions and emotional regulation. It was observed that individuals with eating disorders showed hyporesponsive (lower responses) in the prefrontal cortex than those with normal weight and eating habits. Contrasting temporal differences were also observed in the orbitofrontal cortex for individuals who binge-eat vs. normal individuals. Therefore, this study provides a missing association between how centers of our brain involved in higher cognitive functions respond to what we eat and how we eat.

Rösch, S. A. et al. (2021) ‘Evidence of fnirs-based prefrontal cortex hypoactivity in obesity and binge-eating disorder’, Brain Sciences, 11(1), pp. 1–15. doi: 10.3390/brainsci11010019.

Take-home lesson

We often observe, absorb, and understand that work cultures across different professional settings have set unreasonable expectations that make us feel miserable and insecure whenever we cannot meet them. In order to fulfill those expectations, we see working with maximum efficiency as the only solution. In an attempt to do that, we always keep our brain at the edge, overload it with things and drag it to the extent that it shuts itself off. Not only that, we also adopt unhealthy eating habits to save time. We do all of this because we believe that we will become more efficient, but is it really the case. The four studies summarized above clearly deviates from our beliefs and show that ill sleeping and eating habits can hamper our performance to a great extent. Therefore if you wish to maximize your performance, you must follow the rule – ‘ Eat healthily and sleep peacefully.’

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