Bruxism, or tooth grinding, is when a person unintentionally grinds or clenches their teeth, usually…
What are parasomnias?
Parasomnias are sleep disorders in which disruptive or unwanted behaviours, sensations or experiences occur. Examples include sleepwalking and night terrors.
Parasomnias may occur in different stages of sleep, or during the transition between sleep and waking. For some people, episodes may occur occasionally and pose little more than a nuisance. However, they may also be frequent and distressing for the person experiencing them and for bed partners or family members.
Parasomnias may occur at any age, but many are more common in children.
Stages of sleep
Although sleep is vital for resting and restoring the mind and body, it is still an active state in which the difference between being awake and asleep is blurred.
During sleep, the body cycles between two stages:
Non-rapid eye movement (non-REM) sleep
When someone first falls asleep, they go into non-REM sleep. This consists of initial stages of light sleep, from which people are usually easily awakened, and later periods of deep sleep, which are important for restoration of the body, but from which it is more difficult to be aroused.
You tend to spend more time in non-REM sleep in the first half of the night.
Rapid eye movement (REM) sleep
A period of REM sleep follows each stage of non-REM sleep. During REM sleep, the brain is intensively active and dreaming occurs. Usually the skeletal muscles (the muscles we use for movement) are paralysed during this stage.
Following the REM stage, a new sleep cycle begins. You tend to spend more time in REM sleep towards the end of the night.
There is a wide range of parasomnias. Some of the most common include:
Sleepwalking occurs during non-REM sleep and tends to occur during the first third of the night.
It can cover a wide range of behaviours, from rising from bed and walking around, through to unlocking doors, leaving the house and even driving a car. Episodes typically last for minutes, but can be longer. Although the person's eyes may be open during sleepwalking, they will generally be unresponsive to communication and may be difficult to wake. After an episode, they are unlikely to remember anything that happened.
Occasional or infrequent episodes of sleepwalking are common, particularly in children. Sleepwalking disorder, which is diagnosed if the behaviour is frequent and causes distress or other problems, is less common and may only affect around 1-5% of the general population  .
There are two specialised forms of sleepwalking:
- Sleep-related eating behaviour, in which the person may be unaware that they are eating, or aware of it but unable to stop, and;
- Sleep-related sexual behaviour (sexsomnia), in which the person performs sexual acts without being aware of it. Sexsomnia is more common in men.
Night or sleep terrors also occur during non-REM sleep. During an episode, a person tends to experience intense fear, often screaming or crying out. Other signs may include sweating and a rapid heartbeat and breathing. Episodes tend to last for minutes, but can continue for longer. During this time, the person will often be difficult to comfort or awaken, but will generally remember little or nothing of the episode.
Night terrors are common in young children and around 2% of adults experience them. 
Nightmares are different from night terrors, in that they occur during REM sleep, are more likely to happen in the second half of the night and are generally remembered. They tend to be long, story-like experiences that cause fear, anxiety and other unpleasant emotions. Nightmares usually end by the person waking and rapidly returning to full awareness. It can be difficult to get back to sleep because of the lingering emotions.
Nightmares tend to become more prevalent in adolescence. In adults, they tend to be more prevalent in women, but decline in both men and women as they get older.
Sleep paralysis is the sense of being awake, but unable to move. It can be accompanied by hallucinations and can occur while falling asleep or waking. Episodes can last for seconds to minutes and be frightening, but they are not a sign of serious health problems.
Sleep paralysis can occur when:
- The muscles relax in the first stages of non-REM sleep while the person is still awake, or;
- The person wakes up before an REM stage of sleep - which temporarily paralyses the muscles - is completed.
Confusional arousals can occur when a person is woken from the deep stages of sleep. The person may react very slowly and have trouble understanding what is being said to them for a period of time. The next day they will often not remember being awakened.
REM sleep behaviour disorder
REM sleep behaviours can be similar to sleepwalking, but occur during REM sleep. They are often behaviours in response to the dream the person is having at the time and so may include crying out or yelling, jumping out of bed and violent behaviours such as hitting or kicking. Unlike sleepwalking, when a person wakes from these episodes they tend to be alert and not disoriented or confused.
Other factors that can increase the risk include:
- Not enough sleep or a variable sleep routine;
- Stress, depression and anxiety;
- Alcohol consumption, and;
A range of medications can trigger parasomnias, including:
- Parkinson's disease medications, such as levodopa;
- Lithium, which may be prescribed for mental disorders;
- Bupropion, which may be prescribed as an aid to stop smoking;
- Antidepressant medications such as amitriptyline, and;
- Hypnotic medications prescribed for insomnia, such as zolpidem.
Other medical conditions that may be associated with parasomnias include:
- Sleep disorders in which breathing is disrupted, such as obstructive sleep apnoea;
- Mental health disorders including obsessive compulsive disorder and post-traumatic stress disorder;
- Head injury and stroke;
- Seizures that occur at night;
- Tourette syndrome, and;
- Parkinson's disease.
Methods for diagnosis
Your doctor will ask questions about behaviours that are disrupting your sleep in order to diagnose a parasomnia and understand how it is affecting your life. Often your sleep partner can provide useful information on the type and severity of symptoms.
They may perform a physical exam to identify any underlying medical conditions that may be contributing to the parasomnia, or to rule out other conditions that may cause similar symptoms.
In some cases, a sleep study, or polysomnography, may be recommended. During this test you will stay overnight in a sleep lab, so that your brain activity, movements and other important information can be recorded while you sleep.
Types of treatment
In many cases, parasomnias do not require any treatment. Particularly with children, they will reduce or disappear over time.
It is not dangerous for a person experiencing a parasomnia to be woken; however, they may be confused or agitated and in some cases even violent. When it is safe, gently directing them back to bed may be all that is necessary.
Your doctor may recommend treatment of any underlying medical conditions that may be contributing to the parasomnia, or altering medications if they are suspected of triggering it.
Taking steps to make sure your quality of sleep is good can also help to reduce parasomnia episodes. These include:
- Getting enough good-quality sleep;
- Having a regular sleep routine;
- Reducing noise and light in the bedroom, which can stimulate parasomnias in some people;
- Dealing with stress, and;
- Reducing or avoiding alcohol intake.
Make the environment safe
If a person is at risk of injuring themselves or others, it is important to take precautions such as:
- Closing or locking doors and windows and blocking stairways with gates;
- Removing sharp, dangerous or fragile items from reach;
- Sleeping on the ground floor, if possible;
- Removing potential trip hazards, and;
- Using alarms to awaken the person as they leave their bed.
For people with REM sleep behaviour disorder, it may also be recommended to take measures such as:
- Placing padding on the floor near the bed;
- Moving furniture away from the bed, and;
- Protecting windows.
If the parasomnia happens at a regular time, a technique called anticipatory awakening may be helpful, particularly with children. This involves awakening the person around 15 minutes before the behaviour usually occurs and keeping them awake until after it usually finishes.
Medications are usually not recommended for parasomnias unless they are causing significant distress, or may result in injury.
Benzodiazepines, such as clonazepam, may be prescribed for a short period to help with sleepwalking and REM sleep behaviour disorder, in order to reduce the behaviours. Dietary supplements of melatonin, a natural hormone made by the pineal gland that is involved with the sleep cycle, may also be recommended for REM sleep behaviour disorder.
Many parasomnias are more common in childhood and tend to reduce over time, although for some people they can be lifelong. In most cases, parasomnias can be managed with good sleep habits.
Episodes of parasomnia may be prevented by reducing your exposure to triggers and having a regular sleep routine.
Some forms of parasomnia, such as sleepwalking and REM sleep behaviour disorder, can carry the risk of the person injuring themselves and others. Taking precautions to make sure people are as safe as possible during these behaviours can help to reduce injury.