What Causes Insomnia? A Look Into Sleep Cycle & Neurotransmitters

Ever complained of difficulty in falling asleep or keeping asleep? A sleep that does not freshen you? If this lasts more than a month while also causing daytime impairment, you could be suffering from what is known as insomnia. The prevalence of chronic insomnia is a staggering 10-15%.[1]

So, is insomnia a disease or a symptom? It can be either. It can be classified as primary or secondary depending on absence or presence of an underlying cause. However, insomnia is usually due to an underlying cause and many disorders manifest as insomnia.

Let us look at what causes insomnia and also try to understand what goes wrong inside the body when you suffer from it.

The causes can be classified into somatic (bodily), mental stressors and lifestyle factors. Bodily factors include ageing, medications that interfere with sleep areas of brain, breathing difficulties such as apnea and personality disorders (perfectionism).[1–3] Mental stressors include unemployment, interpersonal conflicts, job insecurity, loneliness and bereavement.[2,3] Lifestyle factors include some poor habits like excessive smoking, alcoholism, lots of coffee, psychoactive drugs and an improper sleep schedule.[2,4]

Some people can be very sensitive to environmental factors including noise (e.g. traffic), light, uncomfortable mattress, temperature change or even the presence of electronic devices.[3]

On the Brighter Side, Some Factors, Which Improve Insomnia, Are the Following:

• Exercise [2]
• Optimism [2]
• Being an Extrovert [2]
• For Some, Repetitive Sounds, E.g., Fan![3]

What is the Architecture of Normal Sleep?

Sleep sneaks into you gradually from Stage 1 to stage 4 and Rapid eye movement (REM) stage. When you are drowsy, arousable, body starting to relax and mind starts slowing down, that’s stage 1. Stages 2, 3 and 4 are known as non-REM stages. Stage 2 (light sleep) proceeds with your body cooling down a bit, movements of eye ball stop and the characteristic sleep spindles appear in the brain (as seen in polysomnography, which is the recording of brain activity). Stages 3 (moderate sleep) and 4 (deep sleep) which are the most restorative and deep sleep phases, and a time when you can be very difficult to wake up. Lastly, Stage 5 (REM sleep) takes precedence and this is when dreams appear, awakenings can happen and your eyeballs rolls rapidly. This cycle of about 90-110 minutes repeats about 4-5 times as we move towards morning.

Interestingly, recent experiments to find what causes insomnia have proven that people with insomnia perceive themselves to be awake in the REM stage of sleep, which is also the stage of dreams.[5] This resonates with an old theory from 1970s: ‘I Am Awake’: insomnia or dream?[6]

Role of Chemicals in Inducing Sleep

Gamma Amino Butyric Acid, commonly known as GABA is a natural neurotransmitter chemical that slows down the brain causing sedation. This property is used to counteract anxiety and convulsions as well. GABA acts on its receptors GABAA in the brain, thus inhibiting firing of the brain neurons.[7]

In a recent study to determine what causes insomnia it was found that people with sleep complaints had lower levels of GABA in areas of brain related to sleep.[8] This emphasizes the importance of GABA in sleep induction and maintenance.

The Link Between Elderly and Insomnia

One thing which comes to the mind thinking of older adults is insomnia. While more common in elderly women, insomnia is more severe when it comes to the male counterparts. This has been linked to reduction in the deep sleep stages (stage 3 and 4 of non-REM sleep).[1] The simple reason behind insomnia in the elderly is the high prevalence of numerous medical conditions that predispose to insomnia as well as poor sleep hygiene (day time naps) that plague the elderly.

How Can Insomnia Harm You?

While it seems like insomnia can be treated easily, in most cases it persists for a long time. In the elderly particularly this can be dangerous and can lead to falls, cognitive decline and cardiovascular diseases like angina. Even in younger ones, chronic insomnia can cause loss of productivity at work and depression.[3] At its worse, people may get addicted to using sedatives and alcohol for sleep.

Given the various causes, both identifiable as well as obscure, insomnia can be a challenge to diagnose and treat. However, its successful treatment can be quite rewarding to your quality of life.

Disclaimer:

I do not have any financial interest in any companies or products featured in this article. The information is for educational purpose and is not intended as medical advice. You should always consult a healthcare practitioner for medical advice.

References:

1. Drake CL, Roehrs T, Roth T. Insomnia causes, consequences, and therapeutics: An overview. Depress Anxiety 2003;18(4):163–76.

2. Bos SC, Macedo AF. Literature review on Insomnia (2010–2016). Biol Rhythm Res 2019;50(1):94–163.

3. Taylor D, Gehrman P, Dautovich ND, Lichstein KL, McCrae CS. Causes of Insomnia [Internet]. In: Handbook of Insomnia. Tarporley: Springer Healthcare Ltd.; 2014 [cited 2020 Jul 29]. page 11–27.Available from: http://link.springer.com/10.1007/978-1-907673-73-3_2

4. Skarupke C, Schlack R, Lange K, Goerke M, Dueck A, Thome J, et al. Insomnia complaints and substance use in German adolescents: did we underestimate the role of coffee consumption? Results of the KiGGS study. J Neural Transm 2017;124(S1):69–78.

5. Feige B, Nanovska S, Baglioni C, Bier B, Cabrera L, Diemers S, et al. Insomnia—perchance a dream? Results from a NREM/REM sleep awakening study in good sleepers and patients with insomnia. Sleep 2018;41(5).

6. Calef V. ‘I am Awake’: Insomnia or Dream? Psychoanal Q 1972;41(2):161–71.

7. Ta QV. Insomnia: An Overview. TTU Rev 2018;1(4).

8. Park S, Kang I, Edden RAE, Namgung E, Kim J, Kim J. Shorter sleep duration is associated with lower GABA levels in the anterior cingulate cortex. Sleep Med 2020;71:1–7.