What is Insomnia?

By Dr Alison Bentley, Restonic Sleep Expert

Understanding symptoms, causes and when to seek treatment

It is easiest to describe insomnia as a reduced quantity of sleep. But, to be insomnia, the reduction in hours of sleep has to cause some kind of problem with daytime function. This could range from poor concentration to memory problems, trouble focusing on tasks that need to be done, and fatigue.

Apart from a drop in immediate daytime function, insomnia can have many long-term effects on health, including cardiac issues and metabolic disorders, such as obesity and diabetes. That makes it important to do something about insomnia.


Acute insomnia occurs when sleep is disrupted due to a specific stressor and in most people only lasts for as long as the stress does, after which it resolves and sleep becomes normal again

There are three main symptoms of insomnia

Most people have more than one of these symptoms and they may not be specific for any particular cause.

Types of insomnia

There are various different types of insomnia.

Acute insomnia occurs when sleep is disrupted

due to a specific stressor and in most people only lasts for as long as the stress does, after which it resolves and sleep becomes normal again. The stress is often psychological. For example, someone might struggle with after the death of a loved one or during a period of intense work stress. It can, however, also be caused by a physical trigger, such as the development of a painful disorder, such as arthritis. Up to a quarter of people with acute insomnia go on to suffer with chronic insomnia.

The definition of chronic insomnia is that the person is experiencing one of the three symptoms restricting sleep at least three days per week for at least three months. At this point, it’s usually not stress causing the sleeplessness, but changes in the way we think of sleep (cognitive issues), as well as some bad habits (behavioural issues) that we adopt to try to get more sleep. These mean we worry more about our sleep and spend longer in bed trying to get more sleep and both of these factors make our sleep problems worse.

There are also many medical and sleep disorders which can present with insomnia. These include depression and anxiety, obstructive sleep apnoea and restless legs syndrome. Many medications used to treat other medical disorders, for example medications that lower cholesterol and antiretrovirals for treating HIV infection, can also interfere with sleep.

Sometimes, poor sleep might be related to a non-medical issue. For example, waking up with aches and pains may simply be due to an ageing mattress. Over years of use, the comfort layers in your mattress break down, which can cause pressure points when you sink onto the firmer support core.

Other signs that your mattress is affecting your sleep can include waking up multiple times a night or taking longer than usual to fall asleep – things that mimic the symptoms of insomnia. So, if you no longer wake up feeling refreshed, your mattress may be at the end of its life, and it’s worth exploring whether this is the case before assuming you’re suffering from insomnia.

Insomnia Causes

How to know if you have insomnia?

Many people believe that if they don’t get a “normal” amount of sleep, they must have insomnia.

The number of hours usually quoted as constituting ‘normal sleep’ is 7 to 8 hours a night. However, this is not quite true. In fact, 7 to 8 hours is the average amount of sleep for a population. But there are many people who need more than that and some that need less.

How do you know how much sleep you need? Experiment. If you are currently getting 6 hours of sleep and feel fatigued, try to get 30 minutes more and see how you feel. The number of hours of sleep that keep you feeling alert during the day is the amount you need. However, if you can only sleep for 5 hours no matter how hard you try, but you don’t feel sleepy during the day, you may be getting enough sleep for you. The number of hours varies between people.

If you feel you may have insomnia, please speak to your doctor. There are a number of conditions that cause insomnia and treatment does not always need to involve sleeping tablets. But ignoring the problem does not result in improvement over time. Once insomnia has become chronic, it will generally continue unless specific action is taken.

Dr. Alison Bentley

Dr. Alison Bentley

Dr. Bentley is a medical doctor with 30 years of experience treating sleep problems in both adults and children. She has a PhD in restless leg syndrome and has worked in private practice, research including academia. She was the founding chair of the Sleep Society of South Africa and has presented at local and international medical and sleep conferences, and in her spare time, she volunteers to build nursery school classrooms. Dr. Bentley believes sleep remains under-researched and aims to improve sleep research and training for doctors. From 2023, Dr. Bentley will be partnering with Restonic SA to share her knowledge and expertise on sleep

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