Experts are still working hard to find out more about the new Omicron variant.
Despite having milder symptoms, the new strain is highly transmissible and symptoms are quite different from previous Covid-19 mutations.
The NHS still lists a high temperature, a new or persistent cough, loss or change in sense of taste or smell as the three main symptoms of Covid.
However, early data suggests symptoms of Omicron are different to these classic three signs - and are often similar to a common cold.
However, some Omicron sufferers have reported a new symptom that has been described as a 'nightmare', The Mirror reports.
Here's what you need to know about it.
What is the Omicron symptom which strikes at night?
Many people who have been infected have reported experienced 'terrifying' sleep paralysis. The NHS explains: “Sleep paralysis is when you cannot move or speak as you are waking up or falling asleep.”
The condition happens when a person cannot move their muscles because they are in sleep mode while their brain is active. It can affect people at any stage of sleep, and sometimes even cause hallucinations such as feeling like someone is pushing you down.
While it can feel 'terrifying' for anyone who experiences it, the NHS has assured that it's harmless and that most people will only get it once or twice in their life.
Though it could be linked to the virus itself, experts believe that sleep paralysis could also be a side effect of increased stress caused by lifestyle changes from the pandemic.
Another common night-time Omicron symptom is night sweats.
Night sweats can leave a person sweating so much overnight that their bedding and clothes become wet, even when sleeping in a cool environment.
NBC News senior medical correspondent Dr John Torres described it as a 'very strange symptom' associated with the Omicron variant.
Night sweats were first linked to the Omicron variant by general practitioner Dr Unben Pillay at a briefing by South Africa’s Department of Health earlier in December.
Many patients confirmed to have the Omicron variant of coronavirus have reported the symptom.
What are the symptoms of Omicron?
The eight early warning symptoms of Omicron according to data from the UK, US and South Africa are:
- Scratchy throat
- Lower back pain
- Runny nose/congestion
- Headache
- Fatigue
- Sneezing
- Night sweats
- Body aches
According to a Covid study from symptom tracker app ZOE, other symptoms that have been reported include congestion, brain fog and skin rashes.
Most symptoms of Omicron have been described as mild but Dr Angelique Coetzee, who first raised the alarm on the new variant, has noted that headaches and sore muscles can be felt more intensely, particularly by unvaccinated people.
What to do if you think you have Covid
If you believe you're experiencing symptoms of Covid, the NHS advises that, you should "self-isolate immediately and get a PCR test”, even if the symptoms are mild.
The health body also recommends that you self-isolate even if you've had the virus before, adding: "You probably have some immunity to the virus but it's not clear how long it lasts."
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