Whether you’re being chased by anything from a dinosaur to a scary clown, we’ve all been jolted awake, afraid of the monsters in our heads. But while nightmares are stressful for the dreamer, night terrors are often more stressful for the observer. We see our partner or child sit bolt upright in bed, scream, and thrash around with a panicked look in his or her wide open eyes. Eventually, they’ll drift back into peaceful sleep.
The kicker? They don’t remember any of it in the morning.
But first, let’s do a quick primer on sleep stages. In 2007, the American Academy of Sleep Medicine updated the phases of sleep. Since 1968, there had been 4 phases plus REM – the stage where dreaming occurs. But in 2007, phases 3 and 4 were consolidated, leaving us with NREM stage 1, NREM stage 2, NREM stage 3, which is also called slow wave sleep, and REM.
Difference 1: Sleep Stages
During REM sleep the brain is as active as when it is awake, and while the jury is still out on the exact function of REM sleep, we do know it’s when dreams (and those chased-by-a-dinosaur nightmares) take place.
Night terrors, on the other hand, occur during NREM stage 3, or slow wave sleep, which is thought to be important for consolidating memories from the day.
During slow wave sleep, the brain rests, as evidenced by less blood flow and a slower metabolic rate within the brain. Also, within each wave, a short period occurs where neurons are silent, giving them a break.
This is why, if you wake someone up from a night terror, they are groggy and befuddled. It takes a few moments to transition out of slow wave sleep, get that blood flowing, and get neurons firing like normal again.
Difference 2: Awakening
Speaking of getting woken up, you’re sure to remember a nightmare that’s jolted you awake. Light sleepers and those suffering from anxiety or depression are also more likely to remember their dreams, as both these disorders increase the likelihood of awakenings – whether micro or extended – in the middle of the night.
However, during a night terror, even though your eyes are wide open, your heart is racing, you may talk or yell, and you’re thrashing around or even running through the house, you’re still technically asleep. In sleep parlance, it’s called a partial awakening, though observers might just call it spooky.
Difference 3: Age and Gender
Nightmares can happen to anyone at any age, though frequency declines from childhood on. Still, about 4% of adults have nightmares at least weekly. Nightmares are more often reported by women, but it’s unclear if women are also more likely to report or not.
For night terrors, the highest frequency is also among kids, affecting up to 6.5% of children. Night terrors may start around age 3 or sometimes earlier, are most common from 5-7, and usually taper off by age 12. Only about 1-2% of the adult population experiences night terrors on a regular basis. In childhood, they’re more frequent in boys, but in adulthood, night terrors affect men and women equally.
Difference 4: Links to Mental Health Challenges
A perpetual question about nightmares is whether they’re a sign of some deeper trouble or if a nightmare can just be a nightmare. Turns out the answer to both parts is “Yes.”
And nightmares are strongly linked to PTSD – in fact, they’re a key symptom of re-experiencing, one of the 3 symptom clusters along with avoidance and hyperarousal.
When nightmares are chronic, turning into night terrors, the individual suffering from PTSD may even avoid sleep, rationalizing “If I don’t sleep, I can’t have a nightmare.”
As a result, many self-medicate by drinking gallons of coffee or loading a schedule so full of work, classes, and other obligations that there’s little chance for sleep. It’s productive, but it makes for a lousy (and drowsy) quality of life.