Interactions between sleep, stress, and metabolism: From physiological to pathological conditions

The scientific paper Interactions Between Sleep, Stress, and Metabolism: From Physiological to Pathological Conditions by Camila Hirotsu et al. explores the complex relationships between sleep, stress, and metabolism. It delves into how modern factors like sleep deprivation and chronic stress are leading to widespread health issues, including obesity and type 2 diabetes. By focusing on the role of the hypothalamic–pituitary–adrenal (HPA) axis, the study explains how disruptions in sleep and increased stress activate neuroendocrine pathways, resulting in metabolic imbalances. Hirotsu et al. emphasize the growing prevalence of metabolic disorders and how poor sleep quality and high stress levels contribute to these conditions. The paper highlights the need for improved sleep hygiene and stress management to combat these rising health concerns.

This study is a comprehensive review of existing research that examines how sleep, stress, and metabolism are connected. It focuses on key systems like the HPA axis, which is critical in how the body responds to sleep and stress. The researchers looked at how disruptions in sleep patterns, such as sleep deprivation or conditions like insomnia and obstructive sleep apnea (OSA), affect the HPA axis.

They also reviewed studies on how these disruptions lead to changes in cortisol production, appetite hormones, and overall metabolic health. The review draws on various studies to clearly understand these relationships, emphasizing the importance of managing sleep and stress to maintain good metabolic health.

One of the key findings is that sleep loss directly affects cortisol levels. Under normal conditions, cortisol follows a daily rhythm, reaching its lowest point (the nadir) at night and rising in the early morning to help wake us up. However, the study points out that "sleep deprivation seems to be related to the elevation of cortisol, reflecting impairment of HPA axis regulation." This means that sleep loss disrupts the normal rise and fall of cortisol, which can lead to constant high levels of this stress hormone. When cortisol levels stay high, it can increase fat storage, especially around the belly, and interfere with how the body regulates blood sugar.

Sleep is also closely linked to the hormones that control hunger. Leptin is a hormone that signals to the brain when we are full, while ghrelin tells us when we are hungry. The study notes, "Sleep curtailment is able to change food intake as a result of decreased secretion of leptin and increased secretion of ghrelin, which leads to increased food intake." When we don't get enough sleep, our bodies produce less leptin and more ghrelin, making us hungrier and more likely to overeat. This can lead to weight gain, especially since people who are sleep-deprived tend to crave high-calorie, low-nutrition foods.

Stress doesn't just make us feel anxious or tense; it also makes us eat more, especially foods high in sugar and fat. The study explains that glucocorticoids (like cortisol) "stimulate appetite and increase body weight through the orexigenic effect of NPY," a hormone that triggers hunger. In other words, when cortisol is elevated due to stress, it signals the body to eat more , particularly "comfort foods" that are high in calories. This increase in food intake contributes to weight gain and metabolic disorders.

The long-term effects of poor sleep and high stress create a cycle of metabolic dysfunction. Chronic sleep deprivation and stress keep the HPA axis in a state of overactivation, which leads to insulin resistance, increased fat storage, and eventually metabolic disorders like obesity and type 2 diabetes. As the paper states, "The bidirectional interaction between sleep and the HPA axis is complex," meaning that both stress and sleep loss feed into each other, worsening their impact on the body's metabolism.

The study emphasizes that the combined effects of poor sleep and chronic stress are leading to an increase in serious health problems like obesity, type 2 diabetes, and other metabolic disorders. One of the key takeaways is that sleep deprivation and stress don't just affect how we feel; they have profound, long-lasting impacts on how our bodies function. The paper explains that "increased levels of cortisol during the nighttime period of total sleep deprivation" are linked to metabolic problems like insulin resistance and obesity.

The scientific paper also highlights that people who experience regular disruptions in their sleep, like shift workers or individuals with sleep disorders, are at a higher risk for these metabolic problems. The disruption of normal sleep patterns throws off the body's natural rhythms, including the production of cortisol and other hormones. This can make it harder to regulate blood sugar and lead to long-term health problems. The study suggests treating sleep problems and managing stress can significantly improve metabolic health.

This study clarifies that good sleep and stress management are essential for maintaining a healthy metabolism. Poor sleep and chronic stress are key drivers of high cortisol levels, increased appetite, and weight gain, all of which can lead to severe health conditions like type 2 diabetes and obesity.

We can significantly lower the risk of developing these metabolic disorders by prioritizing sleep hygiene, reducing stress, and possibly targeting hormonal imbalances like elevated cortisol. Understanding the powerful connection between sleep, stress, and metabolism offers practical steps to living a healthier life.