What is insomnia?

Experiencing one or two nights of restlessness and sleeplessness every now and again does not mean that one has developed insomnia (pronounced ‘in-som-ne-ah’). Instead, experiencing repetitive difficulties (at least 3 times a week or more) with initiating sleep (i.e. taking longer than 30 minutes to fall asleep), maintaining a state of sleep (for longer than 6 hours) or not enjoying a sufficient quality of sleep (i.e. waking at least 3 times during the night, and having difficulties falling back asleep) typically characterise this common medical complaint.  (1) 

A person suffering from insomnia will most likely have the opportunity to sleep, with ample time to get in a full night’s rest, but still have difficulty in attaining the quality of sleep necessary for normal function. A lack of quality sleep that is chronically non-restorative negatively impacts daytime functioning, leaving a person feeling dissatisfied and unrefreshed.

The number of hours of sleep required to get a good night’s rest tends to vary somewhat from person to person. For this reason, the number of hours a person is able to sleep doesn’t necessarily define insomnia. Sleep quantity tends to change as we age and, what we regard as an adequate amount of sleep may decrease (i.e. many seniors retire to bed early and rise early the next morning). Also, as we get older, our bodies produce less of the hormone melatonin, which helps to regulate sleep and wakefulness, and this alters our circadian rhythms. 

Insomnia may be caused by an underlying health condition or psychiatric disorder, medication and substance use, stress, bad sleeping habits, and changes to one’s life, job or sleeping environment. It can however, also be diagnosed as a stand-alone condition.

Sleep disturbances that are most typical of insomnia include:

  • Problems with falling or staying asleep
  • Waking during the early hours of the night or early morning
  • Waking numerous times (more than once) during the night or early morning

Sleep disturbances that characterise insomnia generally stem from a circadian rhythm disruption, which results in poor quality sleep. This can cause daytime dysfunction. A circadian rhythm is something like the body’s ‘internal biological clock’ and helps to regulate the timing of sleepiness / sleep and daytime wakefulness.

Found in most living things, including animals and plants, circadian rhythms are the body’s way of responding to light and darkness.

Circadian rhythms have a direct influence on a person’s sleep-wake cycles, the timing of hormone secretion, digestion and eating habits, as well as body temperature. An irregularity in these rhythms can lead to the development of sleep disturbances, headaches, memory and concentration issues, as well as impact risk factors which have an effect on our health and lead to conditions like obesity and mood disorders such as depression and bipolar disorder.

Sleep deprivation (restriction) or short duration sleep can easily be confused with insomnia. Here’s how to tell the difference between these conditions:

  • Short sleep duration: While only enjoying snatches of sleep is common among those who have insomnia, there are many people who can function successfully throughout the day with only a few hours sleep per night. A person who is able to function normally without much difficulty or residual sleepiness, with only a few hours of sleep a night (less than 7 hours per 24-hour period) is known as a ‘short sleeper’. (2) These individuals generally do not have trouble falling asleep and maintaining sleep, which those suffering from insomnia do. It is also quite common for us to require fewer hours of sleep as night as we age, without feeling any residual effects. This does not necessarily mean that older individuals develop insomnia during their later years. Rather, residual sleepiness during the day and difficulties with normal function, as well as dysphoria (a general dissatisfaction with life) are more common in those experiencing insomnia regardless of their age.
  • Sleep restriction: Reduced sleep time and decreased functional ability is common among those who experience either sleep restriction or insomnia. One of the main differences is that a sleep restricted individual will be able to initiate sleep quickly and maintain normal sleep when an opportunity presents itself. An insomnia sufferer on the other hand, will struggle to initiate and or / maintain sleep despite having ample opportunity to do so.


1. US National Library of Medicine - National Institutes of Health. 15 August 2007. Insomnia: Definition, Prevalence, Etiology, and Consequences: [Accessed 04.08.2018]

2. Centers for Disease Control and Prevention. 2 May 2017. Sleep and Sleep Disorders: Data and Statistics: [Accessed 04.08.2018]

NEXT Understanding sleep and wakefulness

Other Articles of Interest