9 Dangers of Insomnia and Health Risks of Too Little Sleep

The importance of sufficient sleep on a daily basis is well known even without the medical science to prove it. We all know how too little sleep can affect our mental, emotional and physical health. Even insufficient sleep on a single night can have pronounced effects by the next days. However, some of these effects can be very serious, even life threatening and not easily resolved in the short term even with proper sleep.

How does insomnia affect health?

Insomnia is defined as a difficulty falling asleep, staying asleep for sufficient periods of time or non-restorative sleep which means sleep that is not refreshing. These sleep disturbances may arise for many reasons although there are instances where the exact cause of insomnia cannot be identified. Whatever the cause of insomnia, it is well known that sleep-related problems have both psychological and physiological consequences.

Sleeping less than 6 hours and poor quality of sleep have been correlated with a host of medical conditions and health risks. From heart disease, strokes and diabetes to obesity and lowered immune defenses, insomnia appears to disturb various organs, systems and processes in the body. Some of these conditions, like heart disease, can be life-threatening and the treatment of insomnia is therefore crucial.

Always consult with a doctor about ongoing sleep problems. Insomnia is a modifiable risk factor and the treatment and management of sleep disorders can help to prevent various conditions.

Read more on insufficient sleep.

Heart Disease, Hypertension and Strokes

The risk of heart disease, like coronary artery disease (CAD) and myocardial infarction (heart attack), is greater among people who suffer with insomnia (1). This may be associated with the increased risk of diabetes as well as hypertension that is also associated with poor quality and insufficient sleep.

People with insomnia and specifically those who sleep less than five hours a day have a five-fold risk of hypertension (high blood pressure). A lack of sleep contributes to strokes through a variety of direct and indirect mechanisms (2). In fact insomnia is considered as one of the important modifiable risk factors of strokes.

This may in part be due to the high blood pressure (hypertension) and diabetes that are associated with insomnia, as well as being major risk factors for having a stroke. In addition, insufficient sleep has been shown to impede stroke rehabilitation and increase the risk of stroke recurrence.

Read more on sleep deprivation effects.


Type 2 diabetes has become a global health problem that is closely associated with a family history, obesity and sedentary lifestyle. There are several other risk factors and one of these is insomnia. In addition, the effect of insomnia on obesity may further contribute to type 2 diabetes beyond the effects of just poor quality sleep.

Studies have shown that the risk of diabetes is greatest in people who sleep for less than 5 hours daily but is also high in people who sleep for 5 to 6 hours a day (3). The third group, people who slept 6 hours or more daily, had a lower risk of diabetes.

Increased Risk of Accidents

Concentration, reflexes and coordination can be impaired by insomnia and this can ultimately translate into an increased risk of accidents. It may be further compounded by poor memory, irritability, depression, anxiety and various other effects associated with insomnia like excessive daytime sleepiness.

A Norwegian study of 54,399 men and women between 20 and 89 years confirmed these findings of the risk of accidents in people who suffer with insomnia (4). In fact, it correlated insomnia with fatal unintentional events which means deadly accidents were more likely to occur with poor sleep.

The study indicated that as many as 1 in 3 deaths could have been prevented if there were no problems with falling asleep, 1 in 10 deaths prevented if there we no problems staying asleep for sufficient periods of time, as well as 1 in 10 deaths prevented if people did not problems with sleep that was unrefreshing (non-restorative sleep).


Studies have shown that depression is 10 times more likely to occur among people who suffer with insomnia. The psychological effects of insomnia can arise even with even one or two days of insomnia. Irritability, difficulty concentrating and poor memory are just some of the symptoms that arise in the short term.

However, mental health conditions like depression are more likely to arise with chronic insomnia. This may be a significant preventative factor for depression (5). Furthermore, depression itself may affect sleep patterns with both conditions ultimately impacting on each other on an ongoing basis.


There are several studies that have correlated the rise in obesity with the prevalence of sleep disturbances in modern society.  This correlation may be due to multiple factors. Lack of sleep leads to fatigue and therefore less physical activity. It also disrupts the hormones leptin and ghrelin which control appetite and satiety.

Irritability, anxiety and depression may also contribute to unhealthy eating habits which could lead to obesity. Irrespective of the mechanism by which insomnia contributes to obesity, the evidence suggests that improved sleep quality and duration are an important part of weight loss and weight management (6).


The immune system is the body’s first line of defense against infectious agents, like viruses and bacteria. It is also an efficient mechanism to neutralize and eradicate these agents when an infection does occur. Sleep has been correlated with weakened immune function and therefore the risk as well as severity of infections.

Immune defenses are a reflection of overall health, ranging from nutrition, hydration, exercise, substance use and any underlying diseases. Studies indicate that sleep plays a role in maintaining immune strength through various mechanisms, including maintaining the circadian rhythm (7).

Substance Dependence

Insomnia has not beeen directly correlated with addiction to substances like sleeping pills. However, in chronic insomnia where sleeping pills are used regularly and particularly among people with a tendency to develop addictions, a dependence to these substances can arise.

Similarly, some people who suffer with insomnia may find a dependence to other central nervous system depressants like alcohol, particularly before bedtime. Substance dependence is also linked to fatigue and depression which are consequences of insomnia.


  1. www.acc.org/latest-in-cardiology/articles/2016/08/02/07/25/insomnia-and-heart-disease
  2. www.ncbi.nlm.nih.gov/pmc/articles/PMC3387919/
  3. www.ncbi.nlm.nih.gov/pmc/articles/PMC2768214/
  4. www.ncbi.nlm.nih.gov/pmc/articles/PMC4196061/
  5. bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-016-1075-3
  6. www.ncbi.nlm.nih.gov/pmc/articles/PMC3632337/
  7. www.ncbi.nlm.nih.gov/pmc/articles/PMC3256323/

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