What Causes Insomnia?

Insomnia has many causes; most of them include some type of disruption of neural regulation of the circadian rhythms and the sleep-wake cycle, which can be due to numerous factors. Before we discuss those factors, let’s discuss the circadian rhythm, sleep homeostasis, the hypothalamic-pituitary-adrenal (HPA) axis, and the pineal gland.

 

Circadian Rhythms, Sleep Homeostasis, the Pineal Gland and the HPA Axis

Circadian Rhythms

Circadian rhythms are cyclical, 24-hour biological processes, which include fluctuations in hormone levels, body temperature, and sleep. In humans, circadian rhythms are a function of several brain regions, but mainly neurons located in the hypothalamus, specifically in an area of the hypothalamus called the suprachiasmatic nucleus (SCN).

Sleep Homeostasis

Homeostasis is the process by which the body attempts to maintain a steady state. The longer you are awake, the more your body ‘craves’ sleep to restore homeostasis. When it comes to sleep homeostasis, the body relies on neurotransmitters and hormones, such as adenosine, corticotropin-releasing hormone (CRH), melatonin, corticotropin, and cortisol. In addition to the hypothalamus, other areas involved in sleep homeostasis include the pineal gland, the thalamus, the pituitary gland, and the reticular formation within the brain stem.

The Pineal Gland

Both circadian rhythms and sleep homeostasis are influenced by the neurochemical melatonin, which is secreted by a gland in the brain called the pineal gland. The pineal gland produces melatonin in response to darkness and inhibits the production of melatonin in response to light. The pineal gland also effects the production of other hormones, such as sex hormones, by influencing the pituitary gland.

The Hypothalamic-Pituitary Axis (HPA)

The hypothalamus and pituitary gland are part of a system called the hypothalamic-pituitary-adrenal (HPA) axis. This axis is responsible for a number of functions, including regulation of the sleep-wake cycle through neural signaling and hormone production.

Primary & Secondary Insomnia

Chronic insomnia can be categorized as primary insomnia, meaning that the patient experiences insomnia as its own distinct disorder, and secondary insomnia, which is due to another cause, such as a medical condition or side effects of medication.  Insomnia has numerous causes, which include:

1. A neurochemical disorder in the pineal gland 1
2. A disorder of the circadian rhythm, which is a function of the suprachiasmatic nucleus (SCN) located at top of the mesencephalon 2
3. A disorder in the HPA axis 3 – 13
4. A result of disorder in the renin-angiotensin-aldosterone (RAA) axis 14
5. A result of hormonal disorder, related to network connections between the brain, pineal gland, autonomic centers and the gonads (what happens is that anytime you have decrease in reproductive hormones, then you disrupt the cortisol regulation, and when you disrupt cortisol regulation then the brain cannot regulate its internal neurotransmitters; you lose sync and you can’t sleep. 3 – 13
6. Dysglycemia (hypoglycemia and hyperglycemia) 15 16
7. Generalized swelling due to liver or kidney disorder-activation of RAAA axis
8. Leaky gut 17
9. Shift in line of pressure (if you have any deviation of body posturing, whether anterior or posterior (pushed forward or pushed backwards). This increases adrenaline, because the brain is always alert)
10. Secondary insomnia, or comorbid insomnia, is insomnia in addition to some other medical condition or side effect of medication.

Many times, patients with other conditions experience insomnia, such as those listed below. Often, the insomnia is due to one or more of the reasons listed above.

• Psychiatric disorders 18, including depression and anxiety 19
• Fibromyalgia Syndrome (FMS) 20
• Irritable Bowel Syndrome (IBS) 21
• Chronic Fatigue Syndrome (CFS) 22
• Attention Deficit Disorder/Attention Deficit/Hyperactivity Disorder (ADD/ADHD) 23
• Autistic Spectrum Disorders (ASDs) 24
• Restless Leg Syndrome (RLS) 25
• Neurodegenerative disorders, such as Parkinson’s disease and Alzheimer’s disease 26
• Multiple Sclerosis (MS) 27
• Amyotrophic Lateral Sclerosis (ALS) 28
• Chronic pain syndromes 29
• Vascular diseases and cardiovascular diseases 30
• Respiratory conditions 31 32
• Plus many, many others

Every condition listed above has some effect on the functioning of the central nervous system (CNS), autonomic nervous system (ANS), peripheral nervous system (PNS), and enteric nervous system (ENS). When the nervous system starts to dysfunction, we end up with myriad symptoms including problems with sleep.

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