London - Dream analysis has long been regarded by medics as no more meaningful than astrology. But scientists now think dreams could provide vital clues about our health – and give early warnings of conditions years before physical symptoms appear.
Exactly why we dream still mystifies scientists – and provokes fierce debate. What is known is that most of us have four to six dreams a night, but we remember only two or three a week. The reason for this is that we recall a dream only if we wake up in the middle of it. If we carry on sleeping when the dream ends, then we’ve forgotten it forever.
Women seem to remember dreams more often than men, possibly because they tend to be lighter sleepers.
We don’t dream all night. The brain starts to create them only when we switch into a particular type of “dreaming sleep” called rapid-eye movement (REM) sleep.
And because this is a light form of sleep, we wake up easily during dreams.
The first bout starts roughly 90 minutes after we drop off.
So what is the latest thinking about the meanings? Whether you’re dreaming more than usual, or having nightmares or strangely vivid dreams, we look at what this might reveal about your health.
NIGHTMARES
Possible causes: Beta-blockers, heart conditions, migraine or sleep deprivation.
The blood pressure pills beta-blockers are notorious for “quite nasty dreams”, says Professor Jim Horne, a sleep expert from Loughborough University.
These widely used medications help to widen blood vessels, but experts believe they might also indirectly alter the balance of certain brain chemicals, which then triggers nightmares.
Bad dreams can also be linked to a faulty heart, according to a study of more than 6 000 people published in the Netherlands Journal of Medicine. This found that suffering from an irregular heartbeat increases the risk of nightmares threefold, while suffering from chest pain increases it sevenfold.
This could be because people with heart problems are more likely to suffer breathing problems, which could lower oxygen levels in the brain.
Nightmares can also be a warning of an impending migraine. These excruciating headaches can strike at night, and one study of 37 patients found they are often preceded by bad dreams that usually involve themes of anger and aggression. One theory is that the headaches can cause changes in the brain.
But it could just be a lack of shut-eye triggering your nightmares.
Too little can trigger the condition sleep paralysis, which affects one in 20 of us at some stage in life, says Dr Nicholas Oscroft, a sleep expert from Papworth Hospital in Cambridge.
This condition leaves a person unable to move for a few moments after they wake up due to a malfunction in the system that controls our muscles. (Muscles are paralysed when we dream so that we don’t act them out and hurt ourselves.)
As if this isn’t bad enough, a person with sleep paralysis will also often experience the feeling that there is someone in the room with them or that someone is pressing on their chest.
Luckily, this usually only lasts a minute or two, but it can leave a person terrified.
MORE DREAMS THAN USUAL
Possible causes: Getting too hot or cold in the night, hormones, chronic pain or coming off antidepressants.
Overheating or feeling chilly at night can lead to us having more dreams, says Horne.
“The more disturbed your sleep – perhaps by being too hot or too cold – the more likely you are to wake up during dreaming sleep, which means you’ll remember your dreams,” he says.
Experts recommend having your bedroom at around 18°C. For the same reason, the fluctuation in a woman’s hormones can also cause her to have more dreams.
“Some women say they have more dreams around the time of their period,” says Horne. “This could be because some women get very uncomfortable, with bloating or cramps causing them to wake up more.”
Insomnia and pain can also cause people to wake up repeatedly during the night, meaning they remember more of their dreams.
Dr Nicholas Oscroft, a sleep expert from Papworth Hospital in Cambridge, says having a few nights of poor sleep will also lead to a night of vivid dreams.
Having too little sleep, say four to six hours, deprives our brain of the usual amount of dreaming sleep, which means we build up a “debt”. Payback comes when we have the first night of proper rest – and we experience much longer periods of dreaming sleep.
This is known as rapid-eye movement rebound.
It can also occur when a patient stops taking antidepressants. This is because many of the commonly used antidepressants can drastically reduce the amount of REM or dreaming sleep, says Oscroft.
DREAMS OF BEING ATTACKED
Possible causes: Alzheimer’s or Parkinson’s.
Acting out stressful dreams, such as when you’re being attacked or chased, can be an early sign of a brain or nerve disease like Alzheimer’s or Parkinson’s, says Oscroft.
People who regularly flail and thrash about during dreams are thought to suffer from a condition called REM sleep behaviour disorder. It’s believed to be caused by damage in the part of the brain that controls our dreaming “safety switch”, which normally prevents us from acting out our dreams.
This condition causes very violent, disturbing dreams. It is a strong predictor of diseases such as Alzheimer’s and can appear up to 10 years before any other symptoms such as memory loss.
“It can be the first symptom we see,” says Oscroft. “I warn people diagnosed with this to look out for other warning signs of neurological disease, such as tremors or memory loss.”
DREAMS THAT WAKE YOU EARLY
Possible causes: Eating a fatty meal, being overweight, stress or depression.
Large, fatty meals tend to sit in the stomach for longer, says Horne. This puts pressure on the valve between the stomach and the gullet and can cause food and stomach acid to splash back up, triggering heartburn.
This usually happens in the first hours after falling asleep, so it is likely to wake someone early in the night and, therefore, in the dreaming stage.
They’re also likely to wake up spluttering as the acid splashes back up the throat.
Acid reflux is also more common in those who are overweight, as the extra fat can press on the valve and weaken it, making waking early on more common.
People with depression or severe stress also seem to enter dreaming sleep much earlier and so have dreams earlier in the night, says Horne, although doctors are not sure why.
MEMORABLE OR BIZARRE DREAMS
Possible causes: Alcohol, infection, anti-malarial pills or menopause.
A late-night tipple can trigger especially memorable dreams just before you wake up, says Horne.
“People can find themselves having powerful, vivid dreams towards the end of the night. This is because the effects of alcohol seem to wear off towards morning, which might affect brain chemicals in some way and cause strange dreams.”
Being under the weather can also cause a surreal half-sleep, half-awake state, triggering bizarre dreams, says Dr Patrick McNamara, a neurologist from Boston University Medical School.
When our body comes under attack from a bug, our immune system needs to use all its power to fight it. Sleep can help, as a particular type of the deep, non-dreaming kind – called slow-wave sleep – seems to boost our defences.
“Any infection increases the amount of slow-wave sleep we have,” says McNamara.
However, this delays the starting point of when we enter dreaming sleep, so “dreaming sleep starts late, and can erupt into consciousness”, he adds. “This leads to vivid dreams and strange hallucinations.”
Medication can also trigger vivid dreams, he says.
“The anti-malarial drug mefloquine is known to trigger ‘epic dreams’ – long stories with lots of colour and unusual characters or bizarre monsters.”
One theory is these drugs disrupt levels of the brain chemical acetylcholine.
Many women find dreams get particularly vivid around menopause, says Horne. This might be due to fluctuating hormone levels.
SEXUAL DREAMS
Possible causes: Increased creativity.
Dreams of a sexual nature are apparent in all ages but are especially common among the over-60s, says psychologist Ian Wallace.
“Many clients in their 60s and 70s report having these. They don’t represent anything about their sex life, but are connected to increased levels of creativity.”
People often take up new hobbies in retirement, which could be why they have more sex dreams. – Daily Mail