Insomnia Knowledge Centre

Insomnia

Insomnia is the perception or complaint of inadequate sleep due to difficulty falling asleep, waking up frequently during the night, waking up early, or experiencing sleep that is non-refreshing, combined with negative effects on subsequent daytime functioning.¹

Factors that may contribute to insomnia include:

• environmental factors
  (e.g., change in timing of the light–dark cycle; uncomfortable, noisy, or hot/cold surroundings; stressful life events)
• a primary sleep disorder
  (e.g., sleep apnoea, periodic limb movement syndrome, circadian rhythm disorder, restless legs syndrome)
• another medical/neurological/psychiatric condition
  (e.g., depression, anxiety, pain or movement disorders)
• medical treatment, alcohol, or dietary stimulants such as caffeine
• behavioural processes
  (e.g., hyperarousal, which involves an increased metabolic rate; conditioning, where patients convince themselves that they will not be able to sleep)
• increasing age.^2-4

Therefore, the underlying cause(s) of insomnia can be complex, as multiple contributing factors may act singly or in combination (Figure 1)

References:
1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Fourth edition text revision (DSM-IV-TR). Washington DC: American Psychiatric Association, 2000.
2. Vgontzas AN, Bixler EO, Lin HM, et al. Chronic insomnia is associated with nyctohemeral activation of the hypothalamic-pituitary adrenal axis: clinical implications. J Clin Endocrinol Metab 2001; 86 (8): 3787–3794.
3. Perlis ML, Giles DE, Mendelson WB, et al. Psychophysiological insomnia: the behavioural model and a neurocognitive perspective. J Sleep Res 1997; 6 (3): 179–188.
4. Kandel ER, Schwartz JH, Jessell TM. Principles of neural science. ^© The McGraw-Hill Companies Inc, 2000.
5. Szuba MP, Kloss JD, Dinges DF (Eds). Insomnia. Principles and management. © Cambridge University Press, 2003.

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