Sleep-related disorders

Insufficient sleep or chronic insomnia is associated with an increased risk of cardiovascular diseases such as high blood pressure, stroke or and myocardial infarction (heart attack).

One of the main mechanisms involved is the loss of the normal overnight drop in blood pressure, known as “nondipping”. In other words, blood pressure does not fall as it normally should during the night and remains elevated. This places continuous strain on the cardiovascular system and can damage the blood vessels.

In addition, sleep deprivation increases activity in the sympathetic nervous system (the body's alertness system) and raises cortisol levels. This situation leads to a state of hyperarousal that affects the way blood vessels functions, makes blood flow more difficult and contributes to the development of atherosclerosis.

Insufficient sleep is also associated with increased systemic inflammation, increased oxidative stress and metabolic disorders such as insulin resistance. All these factors contribute to cardiovascular risk.

From a clinical perspective, patients with insomnia are more likely to suffer from high blood pressure, arrhythmias and coronary heart disease. Sleep apnoea (interruptions in breathing during sleep) is in itself a cardiovascular risk factor, even in the absence of other risk factors.

Sleep plays a key role in the proper functioning of the immune system.

Not getting enough sleep or sleeping poorly reduces the body’s ability to defend itself against infections and diseases. Even a single night of poor sleep can reduce the activity of natural killer (NK) cells, which play a vital role in immune surveillance.

Biologically speaking, sleep deprivation increases levels of pro-inflammatory cytokines, leading to a state of low-grade chronic inflammation. This state has been linked to cardiovascular, metabolic and autoimmune diseases. In addition, people who do not get enough sleep have a weaker immune response and have been shown to produce fewer antibodies, reducing the effectiveness of vaccination.

In the long term, chronic insomnia increases susceptibility to infections, as well as their severity and may contribute to the development of autoimmune diseases.

On the other hand, a weakened immune system can also exacerbate sleep disorders, as inflammatory processes disrupt sleep and poor sleep increases inflammation.

Lack of sleep or insomnia has a direct impact on the perception of pain. Sleep deprivation increases sensitivity to painful stimuli (hyperalgesia) and reduces the nervous system’s natural ability to modulate pain. As a result, stimuli that would normally be tolerable may be perceived as more intense and unpleasant.

The relationship between sleep and pain is bidirectional. In people with chronic pain, insomnia is very common and can contribute to increased pain intensity, fatigue, emotional sensitivity and functional impairment. At the same time, pain can make it harder to fall asleep and stay asleep. This creates a vicious circle in which pain interferes with sleep, while lack of sleep intensifies the pain.

This link is particularly evident in conditions such as fibromyalgia, chronic headaches and lower back pain. For this reason, improving sleep is part of the therapeutic approach to these disorders. Better sleep can help to reduce pain intensity, improve quality of life and increase the effectiveness of pain-relieving treatments.

Insufficient or fragmented sleep affects the way the body processes glucose and may contribute to the development of type 2 diabetes. One of the main mechanisms is a reduction in insulin sensitivity, which forces the body to produce more insulin in order to maintain normal blood glucose levels.

Furthermore, a lack of sleep disrupts the hormonal balance. Cortisol levels increase, and other hormones involved in metabolic regulation are also affected. These changes can lead to high blood glucose levels (hyperglycaemia) and metabolic disturbances. Even short periods of sleep deprivation can cause changes similar to those seen in people with prediabetes.

Sleep apnoea also plays an important role. Repeated interruptions to sleep promote insulin resistance and can make it difficult to control blood glucose levels in people with diabetes. For this reason, insufficient sleep and sleep-related breathing disorders are considered modifiable risk factors for both the development and progression of type 2 diabetes.

Lack of sleep or insomnia can significantly disrupt the mechanisms that regulate hunger and the body's energy balance.

Lack of sleep or insomnia disrupts the mechanisms that regulate hunger and the body's energy balance. Lack of sleep increases levels of ghrelin, the hormone that stimulates hunger, and reduces levels of leptin, the hormone that triggers the feeling of fullness. This imbalance leads to an increase in appetite and a preference for foods that are high in calories, fat and sugar.

Furthermore, the tiredness resulting from poor sleep reduces physical activity and energy expenditure. At the same time, insufficient sleep affects metabolism and increases cortisol levels, factors which promote fat accumulation, particularly in the abdominal area.

The relationship between obesity and sleep is also bidirectional. Excess weight increases the risk of developing sleep apnoea, and this condition can further worsen sleep quality. As a result, a vicious circle is created, making both weight loss and improvements in sleep more difficult.

Sleep is a fundamental pillar of mental health. Insufficient or poor-quality sleep disrupts the brain mechanisms that regulate emotions and impulse control, which can lead to increased irritability, anxiety, emotional instability and difficulties in managing stress.

In the short term, lack of sleep affects concentration, memory and decision-making. In the long term, insomnia is associated with an increased risk of developing psychiatric disorders, particularly anxiety and depression. Furthermore, disturbances in REM sleep can make it more difficult to process emotions and reduce our ability to adapt to stressful situations.

The relationship is bidirectional: mental health conditions can cause or exacerbate insomnia, and insomnia can contribute to their onset and persistence. For example, anxiety is often associated with difficulty falling asleep, while depression is linked to waking up too early and changes in REM sleep. Disturbances in the sleep-wake cycle are also common in bipolar and psychotic disorders.

Sleep disturbances are common during menopause. The decline in oestrogen and progesterone levels affects the mechanisms that regulate sleep and increases the likelihood of developing insomnia.

In addition, night sweats and hot flushes can repeatedly interrupt sleep, leading to more fragmented sleep and feelings of tiredness during the day. These changes can have a significant impact on physical and emotional wellbeing.

Insomnia during the menopause is also associated with increased irritability, anxiety and depressive symptoms. On a physical level, a lack of sleep can contribute to weight gain, increase cardiovascular risk and contribute to metabolic disorders. Therefore, addressing sleep problems during this stage of life can have important benefits for health and quality of life.

Sleep plays a vital role in the proper functioning of the brain, contributing to processes such as recovery, metabolic regulation and memory consolidation. Sleep also supports the removal of waste products through the glymphatic system, although this mechanism is still being studied, particularly in humans.

Insufficient, fragmented or poor-quality sleep can affect memory, attention and processing speed. In the long term, some studies have linked poor sleep with an increased risk of cognitive decline and dementia. However, this relationship is probably bidirectional: sleep disorders may act as a potential risk factor or contribute to the worsening of the condition, but they may also be a symptom or an early manifestation of the disease itself. Sleep also depends on brain circuits that regulate the sleep-wake cycle, alertness and the quality of sleep, including deeper areas of the brain that can be affected by neurodegenerative diseases.

Sleep disorders are common in many neurological conditions. REM sleep behaviour disorder can occur as a characteristic feature in Parkinson’s disease or in dementia with Lewy bodies. In Alzheimer’s disease, it is common to experience night-time awakenings, daytime sleepiness, confusion in the late afternoon or evening, and disturbances to the sleep-wake cycle. Sleep problems are also common in people with multiple sclerosis, stroke and epilepsy, as a result of both the conditions themselves and the treatments used.