Hypnagogia (also spelled hypnogogia) is a disorder usually described as sleep paralysis, although this definition does not indicate all possible symptoms. In the transition periods of waking up or falling asleep sufferers of hypnagogia feel awake in the mind but paralyzed in the body. These episodes can be quite frightening and hypnagogia is thought to be the origin of stories of demonic or extraterrestrial visits. Studies performed in sleep labs show that while a patient with hypnagogia is awake and aware of their surroundings, instruments measuring brain waves record their brain as asleep.
Many with hypnagogia experience a feeling of falling, auditory or visual disturbances and some report feeling joy. Usually the feeling is short. It is suspected that hypnogogia is a symptom of narcolepsy but there is still much research to be done and this is only one theory. Some sleep researchers make the distinction between hypnagogic hallucinations (which take place in the transition from wakefulness to sleep) and hypnopompic hallucinations (in the transition from sleep and waking.)
Imagine awaking to strange faces and voices but you cannot respond or wake up. Sufferers report an accompanying feeling of dread. Some feel they cannot breathe. A University of London study found that up to 40% of the population has experienced hypnogogic visions at some point and around 5% have had intense experiences.
Imaginary sex with witches and extraterrestrials
Throughout history people have recorded stories of visitors during sleep. A demon – called a succubus or incubus – is said to attack or molest the sleeper and through magic prevents the sleeper from fighting back. Many report a witch is sitting on their chests, preventing them from moving. In some stories, the demon has sexual relations with the sleeper. In recent decades, with stories of UFOs, the stories have often been of extraterrestrial visitors who use advanced technology to stop the human from moving. One theory is that the mind constructs a story to try to make sense of the hypnagogia. These stories may be generated by the mind to explain the strange experience of sleep paralysis during or near the dream-intensive REM state. Stories about witches and aliens are part of the hypnagogic hallucinations. Indeed, some of those who claim to have been abducted from their beds by UFOs claim that the alien handling of their bodies include sexual experimentation. Sex with a succubus or extraterrestrial may be the mind’s way of explaining erections, which men experience in the early morning before waking – a period when hypnagogic hallucinations are likely to happen.
What sets off hypnagogia? When we go into REM sleep our brain restricts our body from moving by blocking the signals to the body that tell us to move. This is so when you are running in your dream, you are not running in bed. The theory most widely accepted is that hypnogogia sufferers’ brains simply do not open up that block quickly enough after waking.
The phenomenon could also be an artifact of the different sections of the brain falling asleep and waking up at slightly different times.
Scientists using electrodes implanted in the human brain found the lower parts of the brain fall asleep before the higher parts. The brain falls asleep from the inside-out rather than from the outside-in. A blogger described this as “the thalamus ‘disconnects’ itself and leaves the cortex freewheeling”. During this freewheeling period the brain is both asleep and awake and the narrative constructing cortex makes up its own reality.
Some people with this disorder try sleeping pills and others learn to live with mild experiences and are alright once they can talk themselves through it. For those with intense experiences, working with a sleep study laboratory can help them better understand what is happening. There are sleep specialists who claim that rolling your eyes back can be enough to signal the brain that you are awake. There have been studies that show a higher incidence of hypnogogia in night workers and people who have been deprived of sleep. This is yet another reason to get your eight hours every night.
Preventing it – or not
Believe it or not, some people actually try to remain in the sleep paralysis state as long as possible. For those with positive experiences, like feelings of joy or seeing kind faces, this can be very relaxing for them. For those who want to reduce or eliminate their hypnagogia, there is medical intervention, or for mild cases there are some recommended simple lifestyle changes. One lifestyle change is to shut off television and relax before bed to reduce brain stimulation before sleeping. Reducing or eliminating drug and caffeine use can reduce the incidence of hypnogogia. Also, the abuse of methamphetamines may cause this disorder.
Treatment of Hypnagogia
Patients are often advised to get used to the phenomenon. It does not require treatment unless the subject finds it unusually disturbing such that it bothers him or her. Treatment is usually psychological rather than medical, if any treatment is given at all.
A combination of lifestyle changes and behavioral therapy can offer relief for the mild to moderate hypnagogia sufferers. An increase in the quality of nutrition, exercise and reduction of stimulants may offer a natural way to treat the problem. For the more serious cases, medication in addition to lifestyle changes and behavioral therapy reduces the severity of the episodes and possibly reduces the number of episodes.
This disorder is characterized by temporary paralysis of the body just after the patient wakes up (medically known as hypnopompic paralysis) and just after the patient falls asleep.
When a person is in the REM stage of sleep, his or her skeletal muscles are paralyzed. This condition is medically known as REM atonia. If the sleeper’s brain comes out of REM before the body, the person can become conscious while still having paralyzed muscles. Microarousals are common between sleep stages. The combination of a dream during REM and the odd sensation of being paralyzed while awake can cause subjects to report surrealist conditions. People report seeing ghosts or feeling someone sit on their chest. The phenomenon known as lucid dream can include this state, although it also may include other states of consciousness.
Another hypothesis is that the brain does not truly awaken during these microarousals in which sleep paralysis is experienced, but only part of the brain is awake. Other parts of the brain continue to dream, which the waking part of the brain sees as hallucinations.
Sleep paralysis attacks typically happen in the first two hours of sleep, during or around the first REM stage of the night. It typically lasts from a few seconds to two minutes.
Doctors have identified certain factors that may aggravate the chances of sleep paralysis. They include:
- Increased levels of stress
- Irregular or insufficient sleep
- Use of hallucinogenic drugs
- Sleeping while lying on one’s back
But this sleep disorder is understudied, compared to many others, and risk and causal factors are not fully characterized.
Almost everyone suffers at least once or twice from sleep paralysis during their lifetime. Some people have it more often, and although it can seem creepy to the sleeper, it is not medically dangerous.
How common is this disorder? Estimates of the prevalence of sleep paralysis are all over the place; studies done in different countries produce vastly different numbers. This is almost certainly due to how the researchers ask the question and what the subjects perceive as abnormal. Superstitions and believe in supernatural forces may play a part. A meta-analysis by researchers at Penn State University found “7.6% of the general population, 28.3% of students, and 31.9% of psychiatric patients experienced at least one episode of sleep paralysis” A study in Japan found 8.3% of teenagers self-reported incidence of sleep paralysis. A poll of Irish university students showed about 20% of respondents got the paralysis.
Doctors have prescribed the benzodiazepine Clonazepam – commonly used for patients with seizures – to help relieve sleep paralysis symptoms in severe cases.