And knowing the difference could be crucial to getting a peaceful night’s sleep.
Groaning at night, known as catathrenia, is a relatively new diagnosis. It usually occurs in the later part of sleep, with each groan lasting up to 50 seconds. The groans may be very loud and can occur hundreds of times a night, according to U.S. research.
Not only do they cause problems with poor sleep and keeping partners awake, but groaners may also experience embarrassment and anxiety, because the noises they produce can sound sexual.
This might help explain why it takes an average of 11 years from the time of the first symptoms for people to seek help.
The good news is that scientists have now identified a ‘gold standard’ for diagnosing the condition, while other research has found that devices that hold airways open at night may help stop it.
Catathrenia was first reported by Belgian doctors in 1983. Sufferers have repeated bouts of groaning or moaning while asleep, each of which lasts between two and 50 seconds, and usually ends with an abrupt snort, although the sufferer usually remains asleep.
The noise is produced when the sleeper is exhaling, which distinguishes it from the sound of snoring, which usually comes during inhaling.
The groaning bouts can come and go throughout the night, although usually they bunch together in the small hours, between two and six hours after falling asleep. Any one stretch of night groaning can last as long as an hour, and in most people, symptoms occur every night.
It’s not known how many people it affects, partly because it’s a relatively recent medical discovery, but also because it may be confused with snoring and other sleep disorders.
What is known is that it’s three times more common in men than woman, according to the British Snoring & Sleep Apnoea Association, and it often starts around the age of 19. It may run in families, and can occur with other sleep problems, such as sleepwalking.
And the noises appear to have nothing to do with what the groaner is dreaming about – people with catathrenia usually have calm facial expressions and seem to be in peaceful sleep, despite the loud noise, according to research from the American Sleep Association. As for causes, one theory is that it’s linked to other sleep-related disorders, such as sleep walking or bed-wetting as a child.
A study of women with catathrenia found that 43 per cent were sleep walkers in childhood, or suffered from night terrors or childhood bed-wetting. These disorders can occur as a result of disruption to so-called rapid eye movement (REM) sleep.
There are different stages of sleep, which we repeat in cycles throughout the night, waking briefly between each cycle. REM sleep comes at the end of each cycle and takes up about 20 per cent of our sleep time. Breathing becomes more rapid, irregular, and shallow, the eyes move rapidly – hence the name – and limbs are temporarily paralysed.
REM sleep is associated with vivid dreams and increased brain activity, and it’s thought the temporary paralysis stops us acting out our dreams. Like nocturnal groaning, we tend to have more REM sleep in the latest sleep cycles in the small hours of the morning.
But other researchers are not convinced nocturnal groaning is related to sleep itself and think it may have a more straightforward mechanical cause.
A study at Osaka University in Japan suggests in some cases it may be linked to contractions of the muscles associated with teeth grinding (or bruxism).
Another study found women with the condition had particular physical characteristics, such as a narrow upper airway, large tongue and a small jaw.
Researchers at Stanford University speculated that the women had evolved an exhaling breathing pattern to get around these problems, which resulted in the nocturnal groaning.
Genes are another candidate. The Stanford University researchers have also found that in 14.8 per cent of cases, there is a family history of groaning.
Perhaps not surprisingly, nocturnal groaning is not good for health, with between 50 and 80 per cent of sufferers having problems related to their poor sleep, including next day fatigue, and chronic sore throats. Depression and anxiety may also be more common in people living with the condition.
However, it’s often their distress and embarrassment about the noise that prompts people to seek medical help, according to scientists at the University of Bologna in Italy.
‘This is especially the case where the loud groaning has a conspicuous sexual connotation which is observed by other family members,’ they concluded. Getting the right diagnosis can be difficult, as it can be hard to distinguish nocturnal groaning from other sleep disorders.
But a study at the University of Rome has shown that polysomnography – monitoring brain waves, the oxygen level in the blood, heart rate and breathing, as well as eye and leg movements during sleep – can detect it.
Researchers found that groans occurred mainly during REM sleep – when regular snoring is uncommon – and that the breathing changed. They concluded that polysomnography should be the ‘gold standard’ for diagnosing catathrenia.
A bigger challenge is to find a treatment for a condition when symptoms can be more of a problem for bed partners. Many drugs have been tried, including various antidepressants.
Various types of upper airway surgery, which can work as a treatment for snoring, have also been used but without success. For some people suffering from catathrenia, a widely-used treatment for obstructive sleep apnoea – a condition linked to snoring where soft tissues in the throat collapse and block the airway – has been found to be effective.
Known as continuous positive airway pressure (CPAP), this treatment involves wearing a mask-like device that delivers a continuous supply of compressed air during sleep to prevent the airways from closing.
Studies showed that nocturnal groaning can coincide with this form of sleep apnoea, though it’s not clear if they are connected.
Treatment with a special kind of mouth guard has also been found to help nocturnal groaners with an abnormality such as a narrow upper airway or small jaw, says the British Snoring Association.
Similar to a gum shield, the custom-made device – known as mandibular advancement device – moves the lower jaw forward to open and widen the airway, making breathing easier.
Any treatment that works not only brings relief to the patient, but also to their family – and, in some cases, neighbours.
Researchers at the Mayo Clinic say the groaning can be loud, and, in some cases, very frequent. Their sleep monitoring showed that during just a single night, one patient groaned 343 times.
So the next time your other half is keeping you awake, it could be worth considering: was that a snore or a groan?