Insomnia is the inability to initiate or maintain sleep, or experiencing poor sleep quality. It is reported in about a third of the population in the US. Its consequences may be serious, impairing daytime functioning. Types of insomnia have been defined based upon the duration and pattern of sleep disruption.
Middle-of-the-night (MOTN) insomnia occurs in 20% to 50% of people, though they may not classify it as a formal sleep disorder. It is short-term when it lasts for less than three months, but beyond this, it becomes chronic.
It is characterized by difficulty in maintaining sleep in one block, resulting in a night-time awakening after several hours of sleep, followed by a significant period of persistent wakefulness before the individual can resume sleep. It is therefore also called difficulty in returning to sleep insomnia.
Health and social risks
Insomnia produces many undesirable effects on those affected as well as on the society in which they live and work. For instance, it is responsible for 50% more healthcare visits, and thus for workplace absenteeism and lower productivity.
Insomnia in the elderly also increases the chances of depression as well as making it more resistant to treatment. The risk of death is higher.
General health was worse in individuals who had MOTN insomnia, though the difference is small.
Factors affecting MOTN insomnia
MOTN insomnia may be caused or exacerbated by factors such as:
- Poor sleep hygiene, such as irregular bedtimes, noisy environment including leaving the television or radio on, an overfull bladder, or having a bed partner who snores or creates other disturbances during sleep times.
- Over-intense exercise within two hours of bedtime
- Intake of caffeine late in the evening, especially for morning persons
- In addition to the physical disturbance, emotional agitation at having been awakened by someone else’s noise can get in the way of falling back to slumber at once.
- Another factor is the low sleep drive at this time because of the previous hours of sleep.
MOTN insomnia is significantly more common in women (approximately 60%), and becomes more frequent with age, though it may happen at any age.
These patients have a higher educational status and a higher net income than those with other types of insomnia. In addition, they were more likely to be whites, suffer from one or more medical conditions, to be unemployed, and to drink alcohol.
In view of the multiple factors affecting sleep, it is important to take a detailed history of the events surrounding bedtime and night-time awakenings. A careful sleep history is important in understanding patients’ complaints of both short-term and MOTN insomnia.
Treatment includes cognitive behavioral therapy (CBT) and pharmacologic modalities.
CBT has been proven to be highly effective in producing both short-term and long-term relief of MOTN insomnia. The drawback is that it requires trained practitioners who are relatively few in comparison to the need. It may also not be eligible for reimbursement. The lack of widespread availability of CBT in insomnia has led to the greater use of medications instead.
Sleep restriction is a behavioral technique which shows great potential in the treatment of MOTN insomnia. This also requires qualified personnel to teach and monitor the therapy, however, limiting its practical use.
Among pharmaceutical agents, the most commonly used include the benzodiazepines, non-benzodiazepines which are GABA-agonists, melatonin receptor agonists such as ramelteon, and certain antidepressants such as trazodone. Antihistamines are used over-the-counter, but they often become ineffective after a short period.
Benzodiazepines may also induce tolerance in some patients. They also have long half-lives. For this reason, the GABA-ergic drug zolpidem and other drugs in its category are becoming more common, with half-lives of 1 - 4.5 hours. It is now prescribed only if the patient can sleep for 8 or more hours following its use. Sublingual use is said to be more effective in inducing sleep more quickly, and maintaining it.
However, all these drugs have significant sedating effects the next day, which are particularly important during activities such as driving, or other occupations that require quick reflex times, good muscular coordination, and unimpaired memory. Cognitive problems may thus pose a significant health hazard in terms of lower levels of alertness and muscle responses the morning after or even later, depending on the drug used. Thus, newer formulations with lower residual sedation are being sought in current research.