"Until recently, there was little agreement about how many people experience sleep paralysis. Studies were sporadic, with little consistency between methods.

But in 2011, clinical psychologist Brian Sharpless, currently a visiting associate professor at St Mary's College of Maryland, conducted the most comprehensive review to date of the condition's prevalence while he was at Pennsylvania State University. It looked at data from 35 studies spanning five decades. Collectively they included more than 36,000 volunteers. Sharpless found that sleep paralysis was more common than previously thought, with almost 8% of adults claiming to have experienced it at one point. That figure is much higher among university students (28%) and psychiatric patients (32%).

"It's really not that uncommon," says Sharpless, who is also the co-author of Sleep Paralysis: Historical, Psychological, and Medical Perspectives.

After experiencing the condition, some gravitate towards supernatural or even paranormal explanations. In reality, says Jalal, the cause is far more mundane. At night, our body cycles through four stages of sleep. The final stage is called rapid-eye movement sleep, or "REM". This is when we dream. During REM, your brain paralyses your muscles, probably to stop you physically acting out your dreams and hurting yourself. But sometimes – and scientists still aren't sure why – the sensory part of your brain emerges from REM prematurely. This makes you feel awake. But the lower part of your brain is still in REM, says Jalal, and is still sending out neurotransmitters to paralyse your muscles.

But for an unlucky minority, the condition proves more testing. Sharpless's research found that between 15% and 44% of those with sleep paralysis experience "clinically significant distress" as a result. The problems usually arise from how we respond to sleep paralysis, rather than the condition itself. Patients find themselves obsessing throughout the daytime about when the next episode might strike.

"It can lead to anxiety at the beginning and end of the night," says Espie. "You grow a network of worry and concern around it. The worst expression of that is turning into a kind of panic attack."

In the most serious cases, sleep paralysis may be a sign of underlying narcolepsy – a more serious sleep condition in which the brain is unable to regulate sleeping and waking patterns, causing someone to fall asleep at inappropriate times."

04/24/23

Check the full article copying the link: https://www.bbc.com/future/article/20230420-the-nightmares-that-paralyse-you-in-your-sleep