”Sleep is that golden chain that ties health and our bodies together.” – Thomas Dekker
Introduction | Memory & Vigilant Attention | Immune System | Mental & Emotional Well-Being | Body Weight | Heart Health | Inflammation | Athletic Performance | Final Thoughts | References | Disclaimer
Introduction
According to data from the World Economic Forum, a staggering 68% of individuals report inadequate sleep at night.[15] On average, adults sleep 6.8 hours on weeknights and 7.8 hours on weekends, with 67% experiencing at least one interruption during the night. Sleep disturbances such as nighttime arousal and insufficient sleep duration exert a detrimental impact on both our physical and cognitive well-being. The repercussions of inadequate sleep extend across various aspects of health, affecting the immune system, cardiovascular health, mental and emotional well-being, as well as memory and attention. The consequences of sleeping too little are profound, underscoring the importance of addressing sleep quality as a paramount goal. Ensuring sufficient and high-quality sleep can significantly enhance not only our health but also our overall quality of life.
Sleep improves memory and vigilant attention
It is easy to see how poor memory and attention are related to sleep deprivation. Still, some studies that looked into these connections gave us more information about the specifics and more precise ways that attention and memory work.
A study conducted by Diekelmann and Bron[1] on the impact of sleep on memory resulted in the conclusion that proper memory consolidation requires both slow-wave sleep [SWS] as well as rapid-eye movement [REM] sleep. Both of these sleep phases contribute to proper memory processing: SWS prepares the memories for long-term storage, whereas REM sleep provides for synaptic consolidation of these memories.
A review of research on vigilant attention was conducted by Hudson et al.[2]. The researchers observed that vigilant attention is very sensitive to sleep restriction, which decreases the psychomotor response time to stimuli. Moreover, they noted that the longer the sleep deprivation period, the slower the recovery and restoration of the response to the baseline marks.
The impact of sleep on the immune system
Numerous scientific studies have examined the relationship between sleep and immune function. It seems as though the two are bidirectionally correlated and impact each other. A sleep cycle affects the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS), which are responsible for regulating adaptive and innate immunity.
A review of research conducted by Besedovsky et al.[3] reported that short sleep duration [<6 h/a night] was associated with a reduced number of naive T-cells that play an important role in an early immune response to new pathogens. Additionally, the researchers stated that short sleep duration [<7h/a night] was found to lower the NK-cell activity [NK-cells are part of the innate immune system]. Lastly, it has been reported that short nighttime rest [≤5 hours/night] was associated with an increased risk of pneumonia. However, participants in these studies who stated that such an amount of sleep was sufficient for them to feel rested were not at risk of developing respiratory tract infections.
A good night's rest is important for mental health and emotional well-being
Sleep is critical for the proper functioning of our brain and central nervous system. Sleep deprivation has been demonstrated to lower emotional regulation and feelings of empathy and has been found to contribute to depression, anxiety, and stress.
A study designed by Killgore et al.[4] followed 26 subjects and measured various parameters connected to emotional well-being at the beginning of the study [baseline] and after a period of 55.5 h and 58 h of wakefulness. The data analysis revealed that, compared to the baseline results, the participants experienced reduced empathy towards other people as well as lowered self-regard, assertiveness, a sense of independence, and self-actualization.
A meta-analysis of studies conducted by Scott et al.[5] focused on the impact of sleep deprivation on mental health, including depression, anxiety, and stress. The authors reported that improved sleep resulted in a medium-sized effect on depression, anxiety, and stress, which led to a reduction in the symptoms of these conditions.
Sleep helps maintain a healthy body weight
We don't immediately realize that our body weight is correlated to the amount of sleep we get at night. There is, however, a growing body of research that examines how the two are related.
Chaput et al.[6] directed a 6-year-long study that followed 43 adult participants who were habitually short sleepers [≤6h/a night]. They were divided into two groups. The first group maintained their short sleeping patterns, whereas the second group was asked to increase their sleep to a healthy level of 7-8 hours a night. The results of this study showed that the body mass index [BMI] and fat mass of the short-sleep duration group who maintained their sleeping habits increased in comparison to the other group. Additionally, the researchers observed that a shift from short to longer sleep duration attenuates fat mass gain.
Antza et al.[7] reviewed epidemiological evidence connecting sleep quality and duration with the risk of developing obesity. They stated that, based on the outcomes of the research, short sleep duration may be associated with an increased risk of developing obesity. In addition, they noted that sleeping too little may reduce the outcomes of weight-loss interventions. Furthermore, obesity is linked with an increased risk of sleep fragmentation[8], which reveals the bidirectional relationship between the two.
Sleep keeps your heart healthy
A major cause of mortality in the world is cardiovascular disease. Among the underlying factors that determine our risk of developing this health condition is our lifestyle, which also includes our sleeping patterns.
A cohort study conducted by Lao et al.[9] on 60,586 Taiwanese residents, age 40 and older, looked at sleep quality and sleep duration and their impact on cardiovascular health. They concluded that both factors—poor sleep quality [dreamy sleep and difficulty falling asleep/use of sleeping pills] and insufficient duration [<6h]—contributed to the increased risk of developing cardiovascular disease.
Similarly, a summary of research presented by Covassin and Singh[10] revealed that short sleep duration [<6/a night] was associated with an increased risk of hypertension [20–32%] and coronary heart disease [relative risk of 1.48]. Interestingly, long sleep duration [≥9 h/a night] was also associated with elevated odds of coronary heart disease [relative risk of 1.38]. Lastly, the reviewers looked at cerebrovascular disease and its connection to sleep duration. Studies have uncovered a link between both short and long sleep durations and the possible increased occurrence of stroke.
Quality sleep reduces inflammation
Sleep is essential for disease and recuperation. It allows the body to perform all the functions that help our body recover faster. On the other hand, poor sleep and sleep disturbances have a counterproductive effect on the functioning of our system and add to the inflammatory conditions we are faced with.
A meta-analysis of cohort and experimental sleep deprivation studies conducted by Irwin et al.[11] inspected the sleeping behaviors that enhance inflammation in our body. They concluded that sleep disturbances as well as longer sleep duration [>8 hours per night] were linked with an increased presence of inflammatory markers such as CRP [C-reactive protein] and IL-6 [interleukin-6]. Interestingly, the participants with short sleep duration [<7 hours a night] did not exhibit any increase in markers of systemic inflammation.
Another study, designed by Dzierzewski et al.[12] investigated the impact of sleep inconsistency on systemic inflammation. The researchers followed 533 participants for 7 days and measured their sleep quality, including the number of awakenings and the time they needed to fall back asleep, overall sleep duration, a latent factor of sleep inconsistency, and inflammatory markers such as CRP, IL-6, and fibrinogen. Their outcomes confirmed that sleep inconsistencies influence the level of inflammatory markers in the system. Moreover, they indicated that it is especially prevalent among women.
Sleep impacts athletic performance
Extreme physical exercise and sports require a good amount of healthy sleep for the body to regenerate itself after such a strenuous activity. Sleep deprivation and sleep fragmentation can disrupt and impact the performance of an athlete.
A review of research led by Vitale et al.[13] linked sleep deprivation in athletes with negative outcomes in both physical and cognitive functions. The decrease in physical functioning was exhibited by poorer running performance, decreased muscle glycogen concentration, reduced strength, minute ventilation, and weaker sport-specific skills such as soccer kicking, serve accuracy in tennis, sprint times, and distance covered. Similarily, the impact of sleep deprivation on cognitive functions was depicted by poor reaction time, poor psychomotor functions, and lowered mood and vigor. At the same time, sleep extension was found to improve both physical and cognitive functioning in athletes.
Another review conducted by Watson[14] reported that sleep deprivation combined with increased training load in athletes is directly related to an elevated risk of injury. Furthermore, the feeling of fatigue that accompanies insufficient sleep is also linked with an increased risk of injury. Lastly, it has been stated that inadequate sleep duration has an immunosuppressant effect on the body and may enhance the susceptibility to upper respiratory tract infections.
Final Thoughts
Sleep is essential for our everyday functioning. It helps us maintain our physical and cognitive health at optimal levels. Sleeping too little has been found to have many negative effects on various aspects of our well-being. The increase in inflammation, poor body weight control, reduced immune function, trouble with memory and attention, and poor emotional regulation are just a few examples of how widespread the impact of this element on our functioning is. Getting enough rest at night [approximately 7-8 hours a night] and taking care of proper sleep hygiene before bedtime promotes health and boosts our body and mind.
References
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