The Mystery Of Sensory Sleep: Why We Don't Feel Anything

Sleep is a period during which the brain is engaged in a number of activities necessary for life. Throughout your time asleep, your brain cycles through two types of sleep: REM (rapid-eye movement) sleep and non-REM sleep. During REM sleep, the eyes move rapidly behind closed eyelids, and the body becomes temporarily paralysed as we dream. During non-REM sleep, the body enters four stages: the first stage comes between being awake and falling asleep, the second is light sleep, and the third and fourth stages are deep sleep. While we sleep, our body's nociceptors (pain receptors) do not fire up as many signals as they do when we are awake, and our brain forces us to relax. However, if the pain is severe enough, it can overcome the numbness and wake us up.

Sleep paralysis

The exact cause of sleep paralysis is unknown, but it is believed to be related to a dysfunction in REM sleep. It may be triggered by various factors, including sleep deprivation, irregular sleep schedules, mental health conditions like anxiety and bipolar disorder, certain medications, and substance use. Sleep paralysis can affect anyone, but it often starts in the teenage years and becomes more frequent in the 20s and 30s.

While there is no treatment to stop an episode once it starts, there are strategies to reduce their frequency. These include improving sleep hygiene, maintaining a consistent sleep schedule, creating a comfortable sleep environment, and addressing any underlying mental health issues or sleep disorders. In some cases, medications may be prescribed to prevent REM sleep or treat associated mental health conditions.

It is important to note that sleep paralysis is typically not dangerous, but recurrent episodes can cause bedtime anxiety and disrupt sleep patterns, leading to fatigue and other health issues. If sleep paralysis is affecting your sleep or causing distress, it is recommended to consult a healthcare provider for guidance and support.

Sleep state misperception

People with paradoxical insomnia experience distress, anxiety, and fatigue. They may function well during the day with no signs of fatigue, but they believe they have insomnia. This discrepancy between their perception and the reality of their sleep can cause conflict with family and friends who don't believe they have a problem. It can also lead to self-treatment with sleep medicines, which can cause confusion, dry mouth, dizziness, or drowsiness.

The causes of paradoxical insomnia are unclear, but it may be related to mental health, mood, or stress. People with this condition may have depression, anxiety, or chronic stress. Research also suggests that physical factors, such as increased metabolism or oxygen levels during sleep, could play a role.

To diagnose sleep state misperception, doctors consider symptoms and may refer patients to a sleep specialist for a sleep study (polysomnography). This involves measuring the amount of sleep, breathing, heart rate, oxygen levels, and body movements during sleep. An electroencephalogram (EEG) test may also be used to measure brain activity.

While there is no standard treatment for sleep state misperception, doctors may prescribe cognitive behavioural therapy for insomnia (CBT-I). This can include sleep hygiene education, stimulus control, and progressive muscle relaxation techniques.

Stress

The specific effects of stress on sleep can vary across individuals. Some people may experience drastic sleep deterioration when stressed, while others may be relatively unaffected. Genetics, family history of insomnia, gender, and environmental stress all play a role in how stress impacts sleep.

The link between stress and insomnia is complex. Stressful life events can trigger insomnia, and the condition can be perpetuated by cognitive and emotional factors such as rumination and worry. These cognitive-emotional responses to stress can exploit vulnerabilities in the sleep system, increasing the risk of insomnia and other sleep disorders.

Additionally, stress-related sleep disturbances are associated with an increased risk of developing mental health disorders, including depression and anxiety. The impact of stress on sleep may also have broader health implications, potentially contributing to cardiometabolic dysregulation and related disorders.

To mitigate the effects of stress on sleep, it is important to modify nighttime behaviours and create a relaxing environment. This can include activities such as yoga and warm baths, reducing screen time before bed, and limiting caffeine intake close to bedtime. Relaxation techniques, such as meditation and breathing exercises, can also help, and there are many apps available to guide people through these practices.

Light and temperature

Our bodies naturally prepare us for sleep by lowering our temperature as bedtime approaches. This is why experts advise against exercising close to bedtime, as it raises our body temperature. Our temperature starts to rise again towards morning, preparing us for wakefulness.

Light also has a significant impact on our sleep. Artificial light from electronic devices, such as phones, computers, and televisions, can trick our brains into thinking it is daytime. This reduces the production of melatonin, a chemical that aids sleep. As a result, we may experience insomnia, or difficulty falling and staying asleep. It is recommended to shut off all digital devices at least an hour before bedtime and to avoid keeping phones near the bed.

The darkness of a room, on the other hand, helps our brains enter "sleep mode." Light-blocking shades or curtains can be beneficial if the bedroom lets in too much light.

In summary, maintaining an optimal temperature and minimizing light exposure in the bedroom are crucial for a good night's rest. Our bodies' natural temperature fluctuations and sensitivity to light are key factors in achieving restful sleep.

Caffeine and alcohol

Caffeine promotes wakefulness by blocking adenosine, a sleep-inducing chemical. Adenosine is a neurotransmitter that builds up in the body during the day, and the sleepier you feel is a result of increased adenosine levels. When you consume caffeine, it binds to the receptors in your brain that are meant for adenosine, thereby inhibiting sleepiness. However, once the effects of caffeine wear off, adenosine molecules can bind to their receptors, causing sleepiness.

The stimulating effects of caffeine can vary depending on individual factors such as genetics, frequency of consumption, and tolerance level. Some people may carry a gene that makes them less sensitive to caffeine, allowing them to consume higher amounts without experiencing its effects. Additionally, regular caffeine consumption can lead to a higher tolerance, requiring increased intake to achieve the same level of alertness. It is important to note that consuming more than the recommended amount of caffeine, which is 400 mg per day or about four cups of coffee, can have negative consequences such as headaches and insomnia.

If you find that caffeine no longer affects you, it may be beneficial to reduce your intake or take a break from it altogether. Gradually tapering off caffeine can help prevent withdrawal symptoms like headaches and irritability.

Mixing caffeine with alcohol should be avoided. Caffeine can block the brain from feeling the sedative effects of alcohol, which may lead to increased consumption and impairment.

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