Types of Insomnia

Insomnia is classified as a sleep disorder, it is a common problem that is thought to regularly affect a third of people in the UK and is particularly common in elderly people. It is where you have difficulty getting to sleep or staying asleep long enough to feel refreshed the next morning, or waking up too early. Both length and efficiency of sleep are important. Insomnia can be transient, intermittent, or long-term. One type of insomnia is short-term insomnia, which tends to be caused by immediate worries such as exams, death of family, or jet lag. Some people suffer short-term insomnia for a short period of time, usually a few days or weeks. The second type of insomnia is long-term insomnia; chronic insomnia describes sleep difficulties lasting more than four weeks. This type of insomnia can be classified as primary and secondary insomnia. Primary insomnia occurs when a person is having sleep problems that are not directly associated with other health conditions or physical causes, for example, a person may be feeling stressed or depressed but these states are not the cause of the insomnia. It may be that they have developed bad sleeping habits but insomnia is the only problem. Sometimes, insomnia may have had an initial cause, but this has disappeared, yet the insomnia persists because the person expects sleep problems. Finally, secondary insomnia is when a person is having sleeping problems because of underlying medical, psychiatric, or environmental causes. This type of insomnia is typical of people who do shift work or have circadian rhythm disorders. Older people tend to experience it because of discomfort while sleeping e.g. from rheumatism.

It is very important to distinguish between primary and secondary insomnia due to the treatment implications. It may not be simple to work out the cause of the insomnia, as we may not know, for example, if stress causes insomnia or if insomnia causes the stress. If insomnia is a symptom of another disorder, then it is important to treat the disorder rather than just the insomnia. For example, if insomnia is the result of chronic depression, it would be unhelpful to simply treat the symptom. Ohayon and Roth studied 15’000 Europeans and found that insomnia more often preceded rather than followed mood disorders such as depression. This means it is more common for insomnia to be caused by a disorder, rather than insomnia to cause another disorder.

Chronic insomnia is highly complex and unlikely to be explained by one single factor. The large number of factors that may contribute to a person’s insomnia makes it very difficult to conduct meaningful research because research tends to find only small effects. This means that research is unlikely to uncover clear solutions to the problem, although one possibility is that primary insomnia is caused by a person’s belief that they are going to have a difficulty sleeping. This expectation becomes self-fulfilling because the person is tense when trying to sleep. One way to treat this is a method based on attribution theory; the insomniac has learned to attribute their sleeping difficulties to insomnia. If they’re convinced the source of the difficulty lies elsewhere, they will then end their dysfunctional attribution. The cognitive approach looks at irrational thoughts; this alongside other theories has led to real world application of effective treatments. Insomniacs were given a pill that would either stimulate them or act as a sedative. Those who expected arousal went to sleep faster because they attributed arousal to the pill and therefore actually relaxed.

Spielman and Glovinsky propose the 3P model to distinguish between predisposing, precipitating, and perpetuating components of insomnia. Predisposing factors include genetic vulnerability for insomnia. Such factors may explain why some people develop insomnia, for example, in response to stress or jet lag. Watson et al found that 50% of the variance for the risk of insomnia could be attributed to genetics; Bonnet and Arand also found that insomniacs are more likely to experience hyper-arousal both when awake and asleep, which would make it much more difficult to sleep. Research suggests physiological factors may also predispose a person to develop insomnia. Secondly, precipitating factors are the events that trigger the disorder in a vulnerable individual. Two individuals may experience the same stressors but only one develops insomnia due to predisposing factors. Environmental triggers for insomnia include stress at work, exams, and shift work. Finally, perpetuating factors are also important i.e. factors that maintain insomnia when the original causes have disappeared or been treated. These factors include being tense when going to bed because of previous sleep problems. Espie suggests that such factors perpetuating are the key to chronic insomnia.

Babies sleep a lot more than children and adults, and also have different sleep patterns and different stages of sleep. They tend to sleep about 16 hours a day, but their sleep is not continuous – they usually wake up every hour or so because their sleep cycles are shorter than the adult 90 minute cycle. Infants have sleep stages that are similar to adult stages called quiet sleep (SWS) and active sleep (REM); at birth there is more active sleep than adult REM sleep, about half of their sleep is spent in active sleep. By the age of six months a circadian rhythm is established and by the age of one, infants are usually sleeping mainly at night, with one or two naps during the day. However, it is not known whether REM activity is accompanied by dreaming as young children cannot give reliable reports. By the age of five, children have EEG patterns that look similar to adults but they are still sleeping about 12 hours per day and have more REM activity, about 30% of sleep time. It is not uncommon for children of this age to experience a variety of parasomnias such as sleep walking or night terrors. During childhood, the need for sleep decrease but in adolescence, it increases to nine or ten hours a night. Circadian rhythms also change so that teenagers feel naturally more awake later at night and have more difficulty getting up early, which is a phase delay. Finally, ‘normal’ adult sleep is typically about eight hours per night, with 25% REM sleep. Childhood parasomnias such as sleep walking are rarer but there is increasing frequency of other sleep disorder such as insomnia or apnoea. With increasing age, the pattern of sleeping changes; REM sleep decreases to about 20% or sleep time and SWS is reduced to as little as 5% or even none at all. Older people also experience phase advance of circadian rhythms, feeling sleepier earlier in the evening and waking up earlier.