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If you've recently been experiencing difficulty falling asleep once you're in bed, and have had many nights where you just can't switch off, then your autonomic nervous system might be out of balance.
This article explains the relationship between sleep and the autonomic nervous system, as well as methods to smoothly switch from the sympathetic to the parasympathetic nervous system for quality sleep.
Are the autonomic nervous system and sleep related?
When the autonomic nervous system is out of balance, your internal clock also gets disrupted, leading to irregular sleep and wake cycles, and a higher likelihood of sleep-related problems.
Conversely, even for people with a well-regulated autonomic nervous system, a lack of sleep can disrupt it. This demonstrates a reciprocal relationship between sleep and the autonomic nervous system.
What is the autonomic nervous system?
The autonomic nervous system is responsible for controlling bodily functions such as organ activity, metabolism, and temperature regulation. It operates 24 hours a day, independently of our conscious will.
There are two types of autonomic nerves: the "sympathetic nervous system," which is active during the day and when we're active, and the "parasympathetic nervous system," which is active at night and during relaxation. The balance between these two types of nerves influences our mental and physical condition.
For example, when the sympathetic nervous system is dominant, the body and mind enter an excited state, leading to increased blood pressure and blood sugar, and dilated pupils.
Conversely, when the parasympathetic nervous system is dominant, the body and mind become more relaxed and enter a state of rest, with effects such as decreased heart rate due to lower blood pressure, constricted pupils, and a drop in body temperature. The ability to recover from fatigue through sleep and rest is due to the activity of the parasympathetic nervous system.
Reasons for autonomic nervous system imbalance
An imbalanced autonomic nervous system means that the balance between the sympathetic and parasympathetic nervous systems is disrupted. Due to various causes, an overactive sympathetic nervous system can lead to symptoms like inability to sleep at night and insomnia.
Stress
When stressed, the sympathetic nervous system becomes overactive, leading to the secretion of hormonal substances like "cortisol" and "adrenaline."
Cortisol and adrenaline are both necessary hormones for the human body, causing effects such as increased heart rate, blood pressure, and blood sugar, immune suppression, and increased gastric acid secretion, all of which result in sympathetic nervous system dominance. However, chronic secretion due to stress can prolong this sympathetic dominance, thereby disrupting the balance with the parasympathetic nervous system, which should ideally take over.
Lifestyle (Rhythm)
An irregular lifestyle, such as a reversed day-night schedule or prolonged sleep deprivation, can lead to the sympathetic nervous system being dominant for longer periods. Additionally, looking at smartphones or computers right before sleep can prevent the parasympathetic nervous system from becoming dominant, leading to an imbalance in the autonomic nervous system.
It's also important to be mindful of extreme dietary imbalances, ensuring that you don't lack the nutrients necessary to maintain the balance of your autonomic nervous system.
Seasonal and environmental changes
Seasonal transitions often bring unstable weather conditions, and life events such as entering or advancing in school, starting a new job, changing jobs, or reassignments lead to significant environmental changes.
Consequently, the physical stress of adapting to the climate and the mental stress of anxiety or pressure can easily disrupt the balance of the autonomic nervous system.
Hormonal balance changes due to menopause, etc.
Because the brain regions that regulate hormone balance and autonomic nervous system balance are located close to each other, a disruption in hormone balance can sometimes lead to an imbalance in the autonomic nervous system.
For example, menopausal syndrome, which is caused by a sharp decrease in female hormones, is a well-known cause of hormonal imbalance.
Autonomic nervous system imbalance check
Here are 20 symptoms often associated with an imbalanced autonomic nervous system, such as anxiety, irritability, insomnia, fatigue, headaches, and stiff shoulders. Please check the items that you experience.
Autonomic Nervous System Self-Check
- Easily fatigued (drowsiness/listlessness)
- Lack of motivation (difficulty persevering)
- Always anxious (lack of confidence in the future)
- Strong desire to avoid meeting people
- Loss of concentration
- Feeling a decline in thinking ability and decision-making
- Irritable for no reason (or vaguely anxious)
- Experience palpitations or shortness of breath
- Frequent colds
- Concerned about swelling
- Headaches
- Back pain
- Symptoms of constipation or diarrhea
- Cold hands and feet
- Numbness in hands and feet
- Prone to stiff shoulders
- Easily stressed and tense
- Feel tired even after sufficient sleep (don't feel refreshed in the morning)
- Wake up earlier than planned in the morning
- Skin is dry, hair is parched
If many items on the 20-item checklist apply to you, or if even one item applies and the symptom is chronic, your autonomic nervous system may be out of balance. Moreover, a chronic imbalance in the autonomic nervous system can lead to "autonomic dysfunction." If you are concerned, consult a medical professional promptly.
How to regulate the autonomic nervous system for better sleep
When the autonomic nervous system is out of balance, it can lead not only to insomnia but also to physical and mental ailments. Therefore, it's important to regulate it through self-care.
1: Reset your internal clock by exposing yourself to morning sunlight
The human body has an internal clock that shifts between an active state during the day and a resting state at night. This internal clock is reset by exposure to strong light in the morning, which triggers the secretion of the sleep hormone "melatonin" approximately 14-16 hours later. By resetting your internal clock in the morning, you can naturally feel sleepy at night and establish a regular sleep rhythm.
It is recommended to open the curtains as soon as you wake up and expose yourself to sunlight for about 15 seconds. Since sunlight is very bright, it is effective even on cloudy or rainy days.
2: Engage the sympathetic nervous system well during the day
To allow the parasympathetic nervous system to be dominant at night, it's important to keep the sympathetic nervous system well-engaged during the day.
For example, exercising during the day facilitates a smoother transition to the parasympathetic nervous system at night. Especially for those who work primarily at a desk or don't move much due to car travel, even if their mind is tired from work, their body might not be, which can make it difficult to sleep. In such cases, make a conscious effort to move your body.
3: Light stretching
Poor blood circulation also affects the autonomic nervous system, so light stretching to improve blood flow and relax muscles is also recommended.
If you spend a lot of time doing desk work, incorporate stretches that you can do while seated.
4: Avoid using your smartphone before bed
Blue light emitted from smartphone and computer screens can inhibit the production of melatonin, which promotes sleep, thus interfering with sleep. Besides its stimulating effect, exposure to bright light in bed can disrupt your internal clock, leading to difficulty falling asleep. Furthermore, prolonged exposure to blue light sources can strain your eyes. Try to practice digital detox for 1 to 2 hours before bedtime.
Additionally, the vast amount of information from smartphones can overstimulate you, making it hard to fall asleep, and incoming calls or vibrations during sleep can lead to shallow sleep. Therefore, avoid sleeping with your phone near your pillow.
How to switch to the parasympathetic nervous system
Busy modern individuals often have their sympathetic nervous system dominating even at night, so it's crucial to relax your mind and body before sleep. Switch to the parasympathetic nervous system by taking a bath, using aromatherapy, drinking herbal tea, or applying acupressure.
1: Bathing
People feel drowsy when their body temperature, which has risen, begins to fall. Therefore, take a bath in lukewarm water (around 38℃) for 25-30 minutes about 1-2 hours before sleep. Bathing can temporarily raise your body temperature, relax your muscles, and activate your parasympathetic nervous system, providing a relaxing effect.
For a half-body bath where you soak up to your abdomen, bathing in water around 40°C for about 30 minutes has similar effects. However, if you take a hot bath over 42°C right before bed, your sympathetic nervous system will become active. If you must take a hot bath, limit it to about 5 minutes.
2: Aroma/Herbal Tea
Aromas are recommended for different settings. For instance, in the living room, use citrus scents like lemon or grapefruit, or rosemary, for a refreshing and relaxing feeling. In the bedroom, use lavender, clary sage, or orange sweet for relaxation and high-quality sleep.
However, scent preferences are individual, so the scents mentioned are not universally effective. Try to use refreshing scents for daytime spaces and relaxing scents for areas where you spend time before bed, according to your preference.
3: Acupressure
When your body is fatigued or you're dealing with worries and stress, your sympathetic nervous system can become dominant, making it difficult to fall asleep. In such cases, try acupressure points that promote the parasympathetic nervous system.
For those who want to improve sleep quality
Achieve quality sleep by being mindful of your autonomic nervous system
When the balance of your autonomic nervous system is disturbed, it can lead not only to insomnia and poor sleep quality but also to various symptoms such as anxiety, tension, fatigue, headaches, and stiff shoulders. To enjoy your daily life, strive for a lifestyle that supports your autonomic nervous system and promotes quality sleep.
If you are already concerned about an imbalance in your autonomic nervous system, consult a medical institution.
