Insomnia is a persistent inability or difficulty in getting to sleep. Insomnia can occur as a condition on its own, but is often associated with other conditions such as chronic pain, depression and anxiety. Approximately 30% of the population of the US suffers from some form of sleep disturbance, with 10% having symptoms associated with insomnia, namely that of an impairment of daytime function. Insomnia may also lead to a weakened immune system, which increases the likelihood of contracting other illnesses.
There are three main types of insomnia: transient insomnia, which is insomnia that lasts less than a week; acute insomnia, aka short-term insomnia, which lasts less than a month; and chronic insomnia, which is insomnia that lasts longer than a month. Those with high levels of stress hormones and drastic shifts in the body’s level of cytokines (small proteins important for cell signalling) are more likely to suffer from insomnia.
Alcohol/opioid/sedative withdrawal, amphetamine use, use of high amounts of caffeine, irregular heart rhythms, the after-effects of surgery, hyperthyroidism and many other conditions may cause insomnia. Exercise-induced insomnia is also common in many athletes. Those who have disturbed sleep have elevated nighttime levels of cortisol and adrenocorticotropic hormone, as well as elevated metabolic rate. Erratic sleeping patterns may also cause insomnia.