Insomnia is the most common sleep disorder and the third most frequent health complaint worldwide – pain and headache being the first two.
So far, in the series of posts related to sleep, we covered the importance of sleep, neuroscience brain waves, sleep stages and healthy sleep habits. In this post, we will cover the causes of insomnia from a neuroscience perspective. The next post will be a continuation of this one and will elaborate on why yoga helps alleviate insomnia, yogasanas, sequences, and guidelines.
Insomnia is characterized by having problems either falling asleep or staying asleep. Clinically, insomnia is considered chronic when a person has difficulty sleeping for over 3 months, at least 3 times a week despite the person having the opportunity to sleep enough.
Clinical symptoms of insomnia include high levels of stress hormones, high body metabolism, high brain activity in some centers, elevated heart rate, high body temperature, heightened alertness, high blood pressure, and an overactive Hypothalamus (one of the main control centers of the brain). All of this suggests that the insomniacs have to deal with chronic activation of the sympathetic nervous system and malfunctioning of some key parts of the brain and their inter-comminication.
Types of Insomnia
There are two main forms of insomnia – primary and secondary.
Primary insomnia is a medical condition in itself and not a symptom of other disorders of medical, emotional or psychiatric type. It generally develops over a period of time. It is usually associated with stress, anxiety or depression – and hence the overstimulation of the sympathetic nervous system and overproduction stress hormones. People with chronic insomnia are known to produce higher levels of stress hormones than normal – particularly cortisol, especially at night. Elevated cortisol level eventually disrupts brain chemistry, causing imbalances in neurotransmitters, including serotonin, dopamine, norepinephrine, and GABA.
Using behavioral techniques, sleep hygiene techniques, relaxation techniques, and nutritional supplements will generally help to reverse primary insomnia. Yoga being a holistic body-mind technique with the ability to influence the nervous system in a significant way can play an important role in bringing a healthy life back in insomniacs. We already covered sleep hygiene and other good sleep habits in a previous post.
Secondary insomnia is the most common type of insomnia. Over 80% of patients with insomnia have secondary insomnia. It is not a disorder but a symptom or side effect of some other pre-existing medical or emotional problems like anxiety, depression, cardiovascular disease, chronic pain, asthma, acid reflux, menopause, urological disorders. It can also be due to a side effect of certain medications for ailments like cold, sinus, asthma. Secondary insomnia may also be due to the overuse of caffeine, nicotine, or alcohol. The treatment for secondary insomnia is to treat the primary condition that is causing secondary insomnia. Yoga may be useful in treating those primary conditions as well. Employing sleep hygiene, Yoga and a few natural supplements may further help.
Causes of Insomnia
There are various causes of Insomnia. Primary causes are stress, anxiety, depression, medication, and hormonal changes. Many of them inter-related. An insomniac can be depressed as well as anxious. Excessive stress can result in anxiety, or anxiety can result in stress. A fear of something can result in sleep disturbances, and sleep disturbance can increase anxiety.
Stress is not a modern world phenomenon. It has been around since the start of civilization. But the nature of stress has changed over a period of time. It has changed so significantly in the last few decades that the human brain has not been able to adapt to those changes. This has led to many disorders that did not exist before – or existed but did not have so much spread. These disorders are psychological and emotional in nature. There is also a new breed of psychosomatic disorders that involves both mind and body. These psychosomatic diseases like psoriasis, eczema, stomach ulcer, hypertension, are physical but are made worse by mental factors such as stress. Because of continuous stress, the nervous system is not able to get into homeostatic balance. This results in overstimulation of sympathetic nervous system with increased stress hormone levels, high brain activity in some centers, elevated heart rate.
Restful sleep is often a challenge for people who struggle with anxiety. if you have anxiety, you are more likely to develop sleep problems, and vice versa. From a neuroscience perspective, anxiety can be categorized, at a high-level, into two – Cortex-based and Amygdala-based.
Cortex-based anxiety is caused by worrying thoughts or images. It is mostly the hyperactivation of the Prefrontal Cortex that keeps your thought processes ON. Prefrontal Cortex is the part of the brain that is associated with thinking, decision making, and attention. When you are not able to sleep, it is very likely because of increased activity in Prefrontal Cortex and Anterior Cingulate. It happens due to rapid change in thoughts resulting from planning or worrying. That’s the reason people with anxiety are also insomniac.
Amygdala-based anxiety may be due to some past fearful experience. Also, a fear of not being able to fall asleep can also become a reason for insomnia. Sleep has a strong impact on the amygdala’s functioning. Studies have shown that the amygdala reacts more negatively to a lack of sleep than other parts of the brain. Lack of sleep leads to heightened anxiety and anxiety leads to disturbed sleep – a vicious cycle. By promoting the activation of the sympathetic nervous system, the amygdala keeps you in an alert state that prevents you from going into a deep sleep. Researchers have found that lower reactivity in the amygdala is associated with getting sufficient REM sleep. And, as covered in the previous post of stages of sleep, REM sleep occurs in later part. Hence it is important that you get a good 8 hours sleep to get rid of amygdala-based anxiety. Both these anxieties are inter-related – one can trigger the other. Worries produced in the prefrontal cortex can compound the problem by exposing you to distressing thoughts that contribute to the amygdala’s activation stress response. And, if you don’t take steps to ensure that you get good sleep, you run the risk of making your anxiety even worse.
Just like anxiety – Insomnia and depression are also related —if you have insomnia, you are more likely to develop depression, and vice versa. Depression is actually a mood disorder that is caused by a deficiency of brain chemicals that regulate mood: serotonin, dopamine, and norepinephrine. These neurotransmitters do far more than just regulate mood. They have also been found to be an integral part of sleep efficiency. Any disruption in them can lead to disturbance in sleep – particularly REM sleep. The connection between insomnia and depression probably has many causes, but one big culprit is a dysfunction of the communication between the Prefrontal Cortex and Limbic system during sleep. (called frontal-limbic communication). The Hippocampus (responsible for memory) and Amygdala are important parts of the limbic system. During sleep, the hippocampus talks to the Prefrontal Cortex by sending bursts of communication, and the Prefrontal Cortex responds to it. Most of it happens during the REM phase of sleep. Having a good REM sleep helps improve this communication.
Hormones affect women more than men. At various stages in life, women face major hormonal changes – menopause being the most significant. The estrogen and progesterone levels decrease during menopause. This can trigger a number of changes in lifestyle, particularly sleeping habits because progesterone is a sleep-producing hormone. Though most of the yoga poses for insomnia are also useful for insomnia induced by hormonal changes in women, we will have a separate post on this topic.
In case of secondary insomnia, the medication or supplements for the primary disease can interfere with sleep.
How Yoga Helps
There is no blanket solution to the problem of insomnia as it is a very complex and highly individualized problem. But the practice of yoga can be helpful to insomniacs as it will not only alleviate the symptoms but will help get rid of the root cause itself. The yoga for Insomnia is like killing several birds with a single stone.
We will cover why yoga works so well in insomnia, yoga poses and guidelines in the next post.
A Medical practitioner’s approval is recommended before practicing any therapy like yoga. Also, do not stop any medication. Yoga should be practiced under the guidance of an experienced yoga teacher.