What is Insomnia?

Insomnia, or sleeplessness, is a sleep disorder in which there is an inability to fall asleep or to stay asleep as long as desired.While the term is sometimes used to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, this sleep disorder is often practically defined as a positive response to either of two questions: "Do you experience difficulty sleeping?" or "Do you have difficulty falling or staying asleep?"
Insomnia is most often thought of as both a medical sign and a symptom that can accompany several sleep, medical, and psychiatric disorders characterized by a persistent difficulty falling asleep and/or staying asleep or sleep of poor quality. Insomnia is typically followed by functional impairment while awake. Insomnia can occur at any age, but it is particularly common in the elderly. Insomnia can be short term (up to three weeks) or long term (above 3–4 weeks), which can lead to memory problems, depression, irritability and an increased risk of heart disease and automobile related accidents.

Those who are having trouble sleeping sometimes turn to sleeping pills, which can help when used occasionally but may lead to substance dependence or addiction if used regularly for an extended period.
Insomnia can be grouped into primary and secondary, or comorbid, insomnia. Primary insomnia is a sleep disorder not attributable to a medical, psychiatric, or environmental cause.It is described as a complaint of prolonged sleep onset latency, disturbance of sleep maintenance, or the experience of non-refreshing sleep. A complete diagnosis will differentiate between free-standing primary insomnia, insomnia as secondary to another condition, and primary insomnia co-morbid with one or more conditions.

DSM-5 criteria for insomnia

The DSM-5 criteria for insomnia include the following:
Predominant complaint of dissatisfaction with sleep quantity or quality, associated with one (or more) of the following symptoms:

• Difficulty initiating sleep. (In children, this may manifest as difficulty initiating sleep without caregiver intervention.)
• Difficulty maintaining sleep, characterized by frequent awakenings or problems returning to sleep after awakenings. (In children, this may manifest as difficulty returning to sleep without caregiver intervention.)
• Early-morning awakening with inability to return to sleep.

In addition,

• The sleep disturbance causes clinically significant distress or impairment in social, occupational, educational, academic, behavioral, or other important areas of functioning.
• The sleep difficulty occurs at least 3 nights per week.
• The sleep difficulty is present for at least 3 months.
• The sleep difficulty occurs despite adequate opportunity for sleep.
• The insomnia is not better explained by and does not occur exclusively during the course of another sleep-wake disorder (e.g., narcolepsy, a breathing-related sleep disorder, a circadian rhythm sleep-wake disorder, a parasomnia).
• The insomnia is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication).
• Coexisting mental disorders and medical conditions do not adequately explain the predominant complaint of insomnia.

note: The DSM-5 criteria for insomnia is intended for use by general mental health and medical clinicians (those caring for adult, geriatric, and pediatric patients).

Types of insomnia

Insomnia can be classified as transient, acute, or chronic.

1. Transient insomnia lasts for less than a week. It can be caused by another disorder, by changes in the sleep environment, by the timing of sleep, severe depression, or by stress. Its consequences – sleepiness and impaired psychomotor performance – are similar to those of sleep deprivation.
2. Acute insomnia is the inability to consistently sleep well for a period of less than a month. Insomnia is present when there is difficulty initiating or maintaining sleep or when the sleep that is obtained is non-refreshing or of poor quality. These problems occur despite adequate opportunity and circumstances for sleep and they must result in problems with daytime function. Acute insomnia is also known as short term insomnia or stress related insomnia.
3. Chronic insomnia lasts for longer than a month. It can be caused by another disorder, or it can be a primary disorder. People with high levels of stress hormones or shifts in the levels of cytokines are more likely to have chronic insomnia.Its effects can vary according to its causes. They might include muscular fatigue, hallucinations, and/or mental fatigue. Chronic insomnia can cause double vision.

Patterns of insomnia

Sleep-onset insomnia is difficulty falling asleep at the beginning of the night, often a symptom of anxiety disorders. Delayed sleep phase disorder can be misdiagnosed as insomnia as it causes a delayed period of sleep, spilling over into daylight hours.
It is common for patients who have difficulty falling asleep to also have nocturnal awakenings with difficulty returning to sleep. Two thirds of these patients wake up in middle of the night, with more than half having trouble falling back to sleep after a middle of the night awakening.
Early morning awakening is an awakening occurring earlier (more than 30 minutes) than desired with an inability to go back to sleep, and before total sleep time reaches 6.5 hours. Early morning awakening is often a characteristic of depression.

Poor sleep quality

Poor sleep quality can occur as a result of, for example, restless legs, sleep apnea or major depression. Poor sleep quality is caused by the individual not reaching stage 3 or delta sleep which has restorative properties.
Major depression leads to alterations in the function of the hypothalamic-pituitary-adrenal axis, causing excessive release of cortisol which can lead to poor sleep quality.
Nocturnal polyuria, excessive nighttime urination, can be very disturbing to sleep.

Subjective insomnia

Main article: Sleep state misperception

Some cases of insomnia are not really insomnia in the traditional sense. People experiencing sleep state misperception often sleep for normal durations, yet severely overestimate the time taken to fall asleep. They may believe they slept for only four hours while they, in fact, slept a full eight hours.

Causes and comorbidity

Potential complications of insomnia.

Symptoms of insomnia can be caused by or be co-morbid with:

• Use of psychoactive drugs (such as stimulants), including certain medications, herbs, caffeine, nicotine, cocaine, amphetamines, methylphenidate, aripiprazole, MDMA, modafinil, or excessive alcohol intake.
• Withdrawal from anti-anxiety drugs such as benzodiazepines or pain-relievers such as opioids.
• Use of fluoroquinolone antibiotic drugs is associated with more severe and chronic types of insomnia.
• Restless legs syndrome, which can cause sleep onset insomnia due to the discomforting sensations felt and the need to move the legs or other body parts to relieve these sensations.
• Periodic limb movement disorder (PLMD), which occurs during sleep and can cause arousals of which the sleeper is unaware.
• Pain An injury or condition that causes pain can preclude an individual from finding a comfortable position in which to fall asleep, and can in addition cause awakening.
• Hormone shifts such as those that precede menstruation and those during menopause.
• Life events such as fear, stress, anxiety, emotional or mental tension, work problems, financial stress, birth of a child and bereavement.
• Gastrointestinal issues such as heartburn or constipation.
• Mental disorders such as bipolar disorder, clinical depression, generalized anxiety disorder, post traumatic stress disorder, schizophrenia, obsessive compulsive disorder, and dementia. or ADHD
• Disturbances of the circadian rhythm, such as shift work and jet lag, can cause an inability to sleep at some times of the day and excessive sleepiness at other times of the day. Chronic circadian rhythm disorders are characterized by similar symptoms.
• Certain neurological disorders, brain lesions, or a history of traumatic brain injury.
• Medical conditions such as hyperthyroidism and rheumatoid arthritis.
• Abuse of over-the counter or prescription sleep aids (sedative or depressant drugs) can produce rebound insomnia.
• Poor sleep hygiene, e.g., noise or over consumption of caffeine
• A rare genetic condition can cause a prion-based, permanent and eventually fatal form of insomnia called fatal familial insomnia.
• Physical exercise. Exercise-induced insomnia is common in athletes in the form of prolonged sleep onset latency.

Sleep studies using polysomnography have suggested that people who have sleep disruption have elevated nighttime levels of circulating cortisol and adrenocorticotropic hormone They also have an elevated metabolic rate, which does not occur in people who do not have insomnia but whose sleep is intentionally disrupted during a sleep study. Studies of brain metabolism using positron emission tomography (PET) scans indicate that people with insomnia have higher metabolic rates by night and by day. The question remains whether these changes are the causes or consequences of long-term insomnia.