Waking up in the morning after having a bad dream at night might not be the best way to start the day, but, a terrifying nightmare can rock you awake from a sound sleep, leaving you scared and confused.

A new study released by psychology researchers Geneviève Robert and Antonio Zadra at the University of Montreal has revealed that nightmares indeed pack a much bigger emotional punch than simply having a bad dream.

Yes there is a difference between nightmares and bad dreams. Zadra sums up the difference between the two in terms of intensity.

Nightmares, according to Zadra are disturbing dreams that actually wake you up and the awakening is directly tied into what was going on in the nightmare. Having a bad dream can also be disturbing, but you continue to sleep and wake up as you normally would. You may also remember the content of the bad dream as soon as you wake up or perhaps later in the day but, “there’s no temporal relationship between the content of the (bad) dream and us waking up from it,” said Zadra.

Zadra adds that nightmares end up giving rise to much more emotional distress than bad dreams do. The researchers asked their volunteer test subjects to rate the intensity of the emotions they experience within their dreams. After analyzing what the volunteers had written the researchers found that nightmares came out to be much more emotionally intense than bad dreams overall.

And, while most people tend to link fear to nightmares and bad dreams, believe it or not it isn’t always the driving factor. While fear does drive a majority of nightmares and bad dreams, Zadra says that about 35% of the nightmares and 50% of the bad dreams of the 10,000 they studied contained other primary emotions such as sadness, confusion, guilt, anger, disgust, and others. As a result, nightmares can intensify a wide range of negative emotions.

So did the researchers find a common theme with nightmares and bad dreams? Zadra said that the most frequently reported themes involved physical aggression or interpersonal conflicts, such as one where the dreamer is having an intense argument or is being humiliated by either a co-worker or family member. Other themes related to helplessness, failure or health related concerns such as being told that you’re about to die since you have cancer or learning of someone else’s death.

Zadra said that being chased, the theme commonly used for nightmares in a number of books and movies, is actually quite rare, occurring in only about 10% of the nightmares and 5% of the bad dreams that were studied.

There are theme differences in the nightmares of men and of women. Robert and Zadra report that nightmares in men were more likely to contain themes of disasters and calamities such as floods, earthquakes, wars and the end of the world, while women were twice more likely than men to have nightmares that contained themes involving interpersonal conflicts with a spouse, co-workers or family member.

While most dreams are visual or a kind of a “cinema of the mind” Zadra says other senses can manifest themselves in nightmares and bad dreams. Dreams can be auditory in nature, Zadra said that for example we can hear people scream or talk to us, hear sirens wailing or a dog barking. On rare occasions Zadra said that we can also feel pain, feel the cold or warmth around us, and sometimes we can also taste or smell things in our dreams.

While an old saying says that eating a heavy meal before bedtime will bring on a bad dream or nightmare, “I think we can probably put to rest the idea that having the pepperoni pizza before going to bed induces nightmares,” said Zadra. While eating a heavy meal at before bedtime can give us indigestion or wake us up during the night, by and large nightmares tend to occur in periods when people are under stress or self-doubt.

Having recurring nightmares may also be linked to a traumatic event. Soldiers returning from war sometimes, dream of the traumatizing events that occurred to them. The researchers also pointed out that the consumption or withdrawal of alcohol or psychotropic drugs could also explain the frequency or intensity of nightmares.

“Nightmares are not a disease in themselves but can be a problem for the individual who anticipates them or who is greatly distressed by their nightmares. People who have frequent nightmares may fear falling asleep – and being plunged into their worst dreams. Some nightmares are repeated every night. People who are awakened by their nightmares cannot get back to sleep, which creates artificial insomnia,” said Zadra.

While they are incredibly disturbing, having frequent nightmares can be treated, according to the researchers. Zadra said that one way to treat recurring nightmares is by using visualization techniques, such when the dreamer learns to change the scenario of his dream and visualize it in his mind by using a mental imagery technique.

A study based on the research conducted by Robert and Zadra was recently published in the journal “Sleep”.

Dr. Zadra joins us on this week’s radio edition of “Science World” to talk about the research he and his colleague Geneviève Robert conducted on bad dreams and nightmares. Tune in (see right column for scheduled times) or check out the interview in the player below.