SLEEP REGULATION

Sleep involves a sequence of physiological states maintained by central nervous system activity that is associated with changes in the peripheral nervous, endocrine, cardiovascular, respiratory and muscular systems (Crisp & Taylor 2005). In current theory, sleep is thought to be an active inhibitory process. The control and regulation of sleep may depend on the interrelationship between two cerebral mechanisms that intermittently activate and suppress the brain’s higher centres to control sleep and wakefulness. One mechanism causes wakefulness, while the other causes sleep (Crisp & Taylor 2005). The reticular activating system (RAS) is located in the upper brainstem. It is believed to contain special cells that maintain alertness and wakefulness. The RAS receives visual, auditory, pain and tactile sensory stimuli (Crisp & Taylor 2005). Sleep may be produced by the release of serotonin from specialised cells in the raphe sleep system of the pons and medulla. This area of the brain is also called the bulbar synchronising region (BSR). As people try to fall asleep, they close their eyes and assume relaxed positions. Stimuli to the RAS decline and, if the room is dark and quiet, activation of the RAS further declines. At some point the BSR takes over, causing sleep (Crisp & Taylor 2005).

DREAMS

Although dreams occur during both NREM and REM sleep, the dreams of REM sleep are more vivid and elaborate and are believed to be important to the consolidation of long-term memory. REM dreams may progress in content throughout the night from dreams about current events to emotional dreams of childhood or the past (Crisp & Taylor 2005).

Most people dream about immediate concerns such as an argument with a partner or worries over work. Another theory suggests that dreams erase certain fantasies or nonsensical memories. Since most dreams are forgotten, many people have little dream recall and do not believe they dream at all. To remember a dream, a person must consciously think about it on waking. People who recall dreams vividly usually wake just after a period of REM sleep (Crisp & Taylor 2005).

INSOMNIA

People commonly complain about insomnia — trouble either falling asleep or staying asleep. Most people experience insomnia transiently, often in relation to one or a number of the above factors (illness, stress, change in sleeping environment). Usual sleeping habits usually return once the acute event or causative factor is over or eliminated. In the short term, having less sleep than normal usually causes no harm. Teaching individuals about the factors influencing sleep may help in improving sleep quality. Often lifestyle and environmental conditions are able to be easily modified, such as reducing alcohol and caffeine intake before bed, not napping through the day and use of stress-modifying techniques.

Chronic insomnia is usually termed as that lasting for a month or longer. It may be the result of an underlying medical, behavioural or psychiatric problem. Depression can often cause insomnia. Chronic insomnia usually requires investigation as to its cause, and treatment other than simple lifestyle and environmental modifications.

SNORING

Snoring is defined as breathing during sleep accompanied by harsh sounds and is caused by any obstruction of the air passages at the back of the mouth and nose. Poor muscle tone, excessive tissue or deformities such as a deviated septum may cause snoring. Obstructed airways due to colds or allergies can also cause snoring. Snoring can also be a symptom of sleep apnoea. The mild snorer should exercise to develop good muscle tone and lose weight if needed (deWit 2005).

OBSTRUCTIVE SLEEP APNOEA (OSA)

This occurs when a person’s airway collapses during sleep. Breathing stops for a variable period until the brain registers a lack of breathing and sends a message to the sleeper. The sleeper rouses slightly, often snorting and gasping, but continues to sleep. Often the individual is not aware that they are rousing, but deep sleep is not maintained. This pattern may repeat itself many times during the night, leaving the person sleep-deprived and fatigued.

Obstructive sleep apnoea (OSA) is a serious and potentially life-threatening condition. The episodes of apnoea during sleep may cause various organ systems to function abnormally and possibly contribute to many disorders such as hypertension, heart attack and stroke. It also commonly leads to excessive daytime sleepiness and poor concentration and potentially increases the risk of having a road accident. Obesity is one of the contributing factors to OSA.

Treatment options may begin with lifestyle changes, if these are indicated, such as weight loss and a decrease in alcohol intake. Referral may be made to an ear, nose and throat (ENT) surgeon to assess whether airway obstruction could be caused by other mechanical factors. A dental splint may be utilised in mild cases of OSA to hold the jaw in a forced-forward position and thus keep the airway open. Moderate to severe sleep apnoea usually requires the long-term use of a nasal continuous positive airway pressure (CPAP) device. This is a mask worn while sleeping. It keeps the back of the throat open by forcing air through the nose, thereby preventing snoring and airway collapse. Clients require education and support to adapt to the use of a CPAP device but, in the long term, OSA can be controlled, and effective restorative sleep restored.

CENTRAL SLEEP APNOEA

Central sleep apnoea occurs when the brain fails to send a signal to the chest and diaphragm to keep breathing. There is no obstruction in the throat but, because of a disorganised breathing control, there is no effort made to breathe. When the signal does come through, breathing is quietly resumed, without the snorts and jerks associated with obstructive apnoea. The condition is usually also managed with CPAP therapy, at low-pressure. ‘Mixed sleep apnoea’ is a combination of obstructive and central apnoea.