25 May 2020 Author : Elsa Parreira We spend about a third of our lives sleeping. A 90-year-old person, for example, was sleeping for 30 years. But sleeping is not a waste of time or a simple state of rest . While we sleep, biological functions essential for our health and well-being take place in our brain and body. Unfortunately, today society does not value sleep properly. This was not always the case, but electric light invaded the night with light, and we stopped having time to sleep. Sleep started to be devalued and seen time wasted; the reduction of sleep time with the consequent increase in the time available to be active or to work, became the rule. Nothing could be more wrong. How important is sleep? Sleep has a restorative function . Sleeping allows our body to restore and regulate important vital functions, such as immune function, which protects us from infections and other diseases, or growth itself. We have genes in our cells (about 8% of our total genes) that are activated only during sleep; these genes have functions associated with metabolism and repair processes. Sleeping is fundamental to our brain . While sleeping, our brain remains very active and in some areas is even more active than during waking. During sleep there is an intense process of functional restructuring in the brain that is crucial for several brain functions, for example memory. After learning, memory consolidation, that is, the transition from short-term memory to long-term memory, which is long-lasting and permanently stored, takes place in a brain structure called the hippocampus. This consolidation of memory is amplified and facilitated during sleep. When we do not sleep, our memory retention capacity decreases by 40%. In people who are sleep deprived, there is a decrease in the activation of the hippocampus, which is a fundamental structure for the consolidation of memory. Likewise, it is also necessary to sleep before learning, so that the brain can prepare for learning and to be able to retain new information. Chronic sleep deprivation On average an adult needs at least 7.5 hours of sleep, but that figure varies from person to person. It is not only the total amount of sleep. Deep sleep time is also important for its restorative function. The number of hours we sleep has been decreasing in recent decades, due to the modern societies. It is estimated that in the 50 of the last century most people slept about 8 hours a night. Currently, we sleep an average of only 6 and a half hours. We do not sleep long enough because we do not give ourselves enough time to sleep. Sleep deprivation is even more serious in people who during the night, as their biological clock continues to maintain the pace related to sunlight, it does not change according to the work schedule. What are the consequences of chronic sleep deprivation? The consequences of chronic sleep deprivation are: At the mental level , in addition to learning and memory difficulties, our cognition capacity is less efficient (as if we had aged a few years), our decision-making and risk assessment skills are compromised and we have mood changes (with irritability and sadness). Sleep deprivation leads to increased reaction time and reduced attention span. Lack of sleep aggravates diseases like depression, epilepsy or migraine. Researchers believe that sleep promotes the removal of toxic products from brain cells , a process that is less efficient when we are awake. Thus, chronic sleep deprivation can be 'toxic' to neurons. But sleep deprivation has many other harmful consequences for our physical health. Sleeping little has negative effects on the cardiovascular system . Sleep deprivation is associated with increased blood pressure, increased risk of myocardial infarction and other cardiovascular diseases. The immune system , a surveillance system that protects us from infections and malignant diseases, is also affected : Sleeping little can cause a reduction of up to 70% in the capacity of our immune system with an increased risk of developing infections and malignant diseases, as has been proven for tumors in the intestine, prostate and breast. Lack of sleep affects body weight : If we sleep 5 hours or less a night, we are more likely to be obese. Lack of sleep seems to increase the release of ghrelin, hormone which increases the feeling of hunger and consequently makes us consume more food, especially carbohydrates. There is also an increased risk of diabetes due to increased cortisol, decreased insulin production and decreased glucose tolerance. Missing one night of sleep is sufficient to create a 'pre-diabetes' state. Chronic sleep deprivation, by increasing the risk of obesity, diabetes, cardiovascular disease, and oncological diseases, contributes to an increase in the mortality rate . Meet the neurology team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
