Sleep is vital for our health. How do we know that? Try living without it. Of course, we all have either tried to do with less sleep or suffered episodes where we could not sleep (insomnia). Sleep is one of those things in the human body that relatively little is known about it despite everyone doing it daily. But mention to anyone that you didn't sleep well last night, and that individual will immediately recognise what you are feeling. But apart from feeling sleepy due to lack of sleep, what are the real effects on the body and brain?

This review will look at the deeper issues (such as the effects on your hormones and inflammatory markers) for chronic insomnia and assume you are well aware of the impact of simply being tired. For that, we need to explore what sleep is and the function of sleep.

What puts us to Sleep?

Naturally, there are a series of chemicals that are released that initiate sleep. Probably the most studied of these chemicals is adenosine. Adenosine firstly accumulates in the ventrolateral pre-optic area, which is thought to trigger sleep. How do we know this? Because our morning friend caffeine is a potent blocker of adenosine So try having a hefty dose of caffeine and trying to fall asleep. Some can tolerate a coffee before bed but take enough caffeine, and sleep becomes a problem.

Sleep is not a homogenous process.

Most people believe that you fall asleep, either stay asleep (or get up for a bathroom break) and wake happily in the morning. The truth is you go through separate stages of sleep, which all have their levels of sleep. Sleep can be broken up into Rapid Eye Movement (REM) sleep and non-REM sleep at a basic level. Below is a graphical representation of the stages and different waves experienced in the brain during sleep.

Our hormones as we sleep

Giving us a clue on the purpose of sleep is the hormones that are released while we sleep. For example, deep sleep induces the release of our growth and repair hormone called growth hormone (GH). So if we lack deep sleep for days in a row, our body fails to repair itself because of the lack of GH release. This gives us the body fatigue people suffer when they lack sleep. If this occurs at an extreme level, body aches become so severe that individuals can suffer conditions such as Fibromyalgia (FM). In a study performed 20 years ago to unlock the mysteries of FM, 25 women with FM and 21 control women had their nighttime GH levels measured as they slept. It was found that women with FM had under half the release of GH as they slept (P<0.05). While the cause of FM is still a mystery to researchers, it is interesting to note that the lack of GH could play a role in the symptoms of FM.

Not only does sleep deprivation cause declines in GH, but it also causes declines in testosterone in men. This is very detrimental because testosterone in men performs many positive functions. For starters, testosterone is critical in maintaining muscle mass in men. And while short bouts of sleep deprivation from time to time is unlikely to drive muscle mass down, chronic sleep problems can lead to reduced muscle mass and an increased fat mass.

Testosterone is found in the brain and is vital for cognition. Testosterone is well known to drive up the gamma-aminobutyric acid (GABA) and serotonin systems in the body. These two neurotransmitters are essential for a healthy mental function, and reduced levels of either or both of these neurotransmitters can lead to anxiety. Chronic effects of these neurotransmitters being depleted can also lead to frank depression.

Inflammatory markers increase when sleep is diminished.

Inflammation in the body is often used in the process of healing. It is only considered a pathology when levels are increased for an extended period (i.e., Chronic Inflammation or CI). CI can lead to numerous pathologies such as heart disease, arthritis or simple unspecified body aches and pains. Chronic sleep deprivation leads to chronic inflammation which can further exacerbate anxiety and depression, which can cause a positive and dangerous feedback loop causing further lack of sleep.

Treating Sleep Disorders

Similar to treating most diseases or pathologies, removing the cause is the first step, so determining the cause of your sleep issue is the first issue to address. If you are staying up late watching TV and lacking sleep solely because of that, then the cause is quickly addressed.
For most insomniacs, the cause may be more challenging to treat, such as financial stressors or relationship problems. Work could be keeping you awake also. For these mental causes of sleep problems, therapies such as Cognitive Behavioural Therapy could be helpful. Other effective treatments are herbal medicines such as valerian, chamomile and kava. But see your health care professional for further advice or if your condition is chronic.

The take-home message

Chronic sleep deprivation can have wide-spreading ill effects on the body. Of course, it makes you groggy and forgetful, and all the classic symptoms of just being well sleep-deprived (we have all been there). However, sleep deprivation can depress testosterone, growth hormone and deplete neurotransmitters such as serotonin and GABA. This can lead to anxiety and depression. Lack of sleep can also increase inflammatory markers, which leads to a whole host of disorders. Thus, it is important to treat chronic sleep deprivation as a severe disease and not dismiss it as ‘just lacking sleep’.  We always recommend checking in with your health care practitioner to work through some solutions to help.


REFERENCES

Effects of adenosine on gabaergic synaptic inputs to identified ventrolateral preoptic neurons. Chamberlin NL, Arrigoni E, Chou TC, Scammell TE, Greene RW, Saper CB Neuroscience. 2003; 119(4):913-8.

Ribeiro JA, Sebastião AM. Caffeine and adenosine. J Alzheimers Dis. 2010;20 Suppl 1:S3-15. doi: 10.3233/JAD-2010-1379. PMID: 20164566.

Sleep cycle oscillation: reciprocal discharge by two brainstem neuronal groups. Hobson JA, McCarley RW, Wyzinski PW Science. 1975 Jul 4; 189(4196):55-8.

Carley DW, Farabi SS. Physiology of Sleep. Diabetes Spectr. 2016;29(1):5-9. doi:10.2337/diaspect.29.1.5

A quantitative evaluation of the relationships between growth hormone secretion and delta wave electroencephalographic activity during normal sleep and after enrichment in delta waves. Gronfier C, Luthringer R, Follenius M, Schaltenbrand N, Macher JP, Muzet A, Brandenberger G. Sleep. 1996 Dec; 19(10):817-24.

Landis CA, Lentz MJ, Rothermel J, Riffle SC, Chapman D, Buchwald D, Shaver JL. Decreased nocturnal levels of prolactin and growth hormone in women with fibromyalgia. J Clin Endocrinol Metab. 2001 Apr;86(4):1672-8. DOI: 10.1210/jcem.86.4.7427. PMID: 11297602.

Herbst KL, Bhasin S. Testosterone action on skeletal muscle. Curr Opin Clin Nutr Metab Care. 2004 May;7(3):271-7. DOI: 10.1097/00075197-200405000-00006. PMID: 15075918.

Hanson JA, Huecker MR. Sleep Deprivation. . In: StatPearls . Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK547676/

Hanson JA, Huecker MR. Sleep Deprivation. . In: StatPearls . Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK547676/

Worley SL. The Extraordinary Importance of Sleep: The Detrimental Effects of Inadequate Sleep on Health and Public Safety Drive an Explosion of Sleep Research. P T. 2018;43(12):758-763.

Leach MJ, Page AT. Herbal medicine for insomnia: A systematic review and meta-analysis. Sleep Med Rev. 2015 Dec;24:1-12. DOI: 10.1016/j.smrv.2014.12.003. Epub 2014 Dec 17. PMID: 25644982.

Guilleminault C. Benzodiazepines, breathing, and sleep. Am J Med. 1990 Mar 2;88(3A):25S-28S. doi: 10.1016/0002-9343(90)90282-i. PMID: 1968716.