Scientists from Oxford, Cambridge, Harvard, Manchester and Surrey universities have warned of the "supreme arrogance" and serious health problems that result from cutting sleep. Sleep can help us lose weight; lost sleep increases the risk of heart attack; napping is a good thing. The benefits of sleep are never ending, and the importance of getting a solid eight hours can't be overestimated, but what about when it goes wrong? What are the negative aspects of a good night's rest?

For many sufferers of sleep disorders (known as parasomnias), and their other halves – a good night's sleep is an elusive thing. As six in every 10 Brits are now sleep deprived, we examine some of the many problems that are keeping us up at night.

Sleep paralysis

Sleep paralysis is the inability to move or speak, experienced during REM (rapid eye movement) sleep, when a person is falling asleep or (less commonly) waking up. The paralysis is harmless but often frightening, and can last for a few seconds or several minutes. These episodes are often accompanied by hallucinations, either of other objects or beings, or of their own body moving (generally falling) uncontrollably. While we sleep, our body allows our muscles to relax. Sleep paralysis occurs when someone wakes up before the mechanism that causes their muscles to relax has stopped working. Sleep paralysis often occurs when people are sleep deprived, so getting eight hours of regular rest a night can help to combat this disorder.

Night terrors

Only when scientists discovered REM sleep did it become possible to differentiate between nightmares and their scarier big brother, night terrors. Night terrors occur on waking from NREM (non rapid eye movement) sleep, whereas nightmares occur during REM sleep, later in the night. Night terrors are common in children, but can continue into - or develop in – adulthood. The person will enter a state of extreme panic, and will often lash out, shout, and scream, but won't remember the incident the following day. In order to break the cycle of night terrors, it can be useful to ensure a person is fully awake before they go back to sleep after a night terror.

Obstructive sleep apnoea (OSA)

During an episode of OSA, a person's throat muscles will relax, causing their airway to close, and them to stop breathing. OSA has two forms: apnoea (total blockage of a person's airway for more than 10 seconds) and hypopnoea (partial blockage for more than 10 seconds). During an episode, a person will awaken and restore normal breathing, but this process may be repeated almost constantly through the night, contributing to fatigue the following day. OSA is relatively common, affecting around 4% of middle-aged men in the UK, and 2% of middle-aged women. It is often seen in overweight people, and can be resolved with weight loss.

Confusional arousals

Confusional arousals occur when a person is woken from a deep NREM sleep, usually in the first half of a night's sleep. They remain in a state of confusion and often act very slowly, which is why the disorder is also known as sleep drunkenness. The person will usually sit up and look around, appearing to be awake and alert, but will often have no memory of this the following day. They are usually harmless, but may be a symptom of another sleep disorder, such as sleep apnoea. Some studies have shown a strong genetic influence in those suffering from confusional arousals: up to 60% of cases had a family history of partial arousals.

Sleepwalking (somnambulism)

The most common sleep disorder, sleepwalking, also occurs during NREM sleep. A person will walk and carry out complex activities while asleep. Often caused by stress or sleep deprivation, sleepwalking runs in families, and a person is 10 times more likely to sleepwalk if a first-degree relative also suffers. While they may be able to navigate obstacles and even send emails or draw pictures, they will look blankly at another person, and their speech is likely to be incomprehensible. Hypnotherapy can be used to treat sleepwalking, and while the best thing to do for a sleepwalker is to guide them safely back to bed, waking someone up can prevent another sleepwalking episode during the same sleep cycle.

Teeth grinding (bruxism)

What is commonly known as teeth grinding is often a problem caused by excessive clenching of the jaw, both during the day and at night. Almost 80% of teeth grinding occurs during sleep, and about 70% of these cases are closely linked to stress or high anxiety. However, drinking alcohol, smoking, and using drugs have also been known to increase instances of teeth grinding. One 2010 BBC article cited the recession as a cause for a vast increase in the amount of teeth grinding seen by dentists. Excessive teeth grinding can cause headaches and earaches, and is most effectively managed by wearing a mouthguard at night.

Sleep sex (sexsomnia)

Sleep sex is when a person (in the vast majority of cases, a man) engages in sexual activity while asleep. Occurring during NREM sleep, sexsomnia is often triggered by stress, drugs or alcohol, and the person is likely to have suffered from other forms of sleep parasomnias. Instances of sexsomnia occur when the person is in bed with someone – it is rare that a person will leave their bed to find a partner while asleep. Sufferers often do not remember the encounter, and it has been used as a defence in cases of sexual assault.

Sleep-related eating disorder (SRED)

SRED usually develops in people who have suffered other forms of parasomnia previously, and is classed as a combination of a parasomnia and an eating disorder. It involves nightly binges, and is mostly found in women, often those who suffer from depression or eating disorders when awake.

REM behaviour disorder (RBD)

People who suffer from this disorder will act out their dreams, making it one of the most dangerous sleep disorders. Lacking the muscle paralysis that accompanies most people's dreaming states, they are often violent and have been known to seriously harm themselves or their partner. Luckily, this disorder is treatable, and in 90% of cases is cured by medication.

Catathrenia

This is also known as nocturnal groaning, which tells you all you really need to know. Occurring both during REM and NREM sleep (although usually during REM sleep), a person will inhale deeply and then hold their breath for a few seconds. Their exhale will be accompanied by a moan or screech, which can be very loud. Because the condition is relatively harmless, there has been little research into its causes. There is debate over whether it results from closure of the vocal chords or narrowing of respiratory airways during REM sleep. There may also be a neurological explanation.