Psychology2016

148 CHAPTER 4

(Horne & Staff, 1983). Perhaps the dreams people have in REM sleep are a way of dealing

with the stresses and tensions of the day, whereas physical activity would demand more

time for recovery of the body in NREM sleep. Also, if deprived of REM sleep (as would

occur with the use of sleeping pills or other depressant drugs), a person will experience

greatly increased amounts of REM sleep the next night, a phenomenon called REM

rebound (Lo Bue et al., 2014; Vogel, 1975, 1993).

An early study of REM sleep deprivation (Dement, 1960) seemed to suggest that

people deprived of REM sleep would become paranoid, seemingly mentally ill from lack

of this one stage of sleep. This is called the REM myth because later studies failed to reli-

ably produce the same results (Dement et al., 1969).

Other early research attempted to link REM sleep with the physical changes that

occur during storing a memory for what one has recently learned, but the evidence today

suggests that no one particular stage of sleep is the “one” in which this memory process

occurs; rather, the evidence is mounting for sleep in general as necessary to the formation

of memory (Ellenbogen et al., 2006; Kurdziel et al., 2013; Maquet et al., 2003; Seehagen

et al., 2015; Siegel, 2001; Stickgold et al., 2001; Walker, 2005).

REM sleep in early infancy differs from adult REM sleep in several ways: Babies

spend nearly 50 percent of their sleep in REM sleep as compared to adults’ 20 percent,

the brain-wave patterns on EEG recordings are not exactly the same in infant REM sleep

when compared to adult REM sleep recordings, and infants can and do move around

quite a bit during REM sleep (Carskadon & Dement, 2005; Davis et al., 2004; Sheldon,

2002; Tucker et al., 2006). These differences can be explained: When infants are engaged

in REM sleep, they are not dreaming but rather forming new connections between neu-

rons (Carskadon & Dement, 2005; Davis et al., 2004; Seehagen et al., 2015; Sheldon, 2002).

The infant brain is highly plastic, and much of brain growth and development takes

place during REM sleep. to Learning Objective 2.3. As the infant’s brain nears

its adult size by age 5 or 6, the proportion of REM sleep has also decreased to a more

adult-like ratio of REM sleep to NREM sleep. For infants, to sleep is perchance to grow

synapses.

Sleep Disorders

4.6 Differentiate among the various sleep disorders.

What happens when sleep goes wrong? Nightmares, sleepwalking, and being unable to

sleep well are all examples of sleep disorders.

What would happen if we could act out our dreams? Would it be

like sleepwalking?

NIGHTMARES AND REM SLEEP BEHAVIOR DISORDER Being able to act out one’s

dreams, especially nightmares, is a far more dangerous proposition than sleepwalking.

Nightmares are bad dreams, and some nightmares can be utterly terrifying. Children

tend to have more nightmares than adults do because they spend more of their sleep

in the REM sleep state, as discussed earlier. As they age, they have fewer nightmares

because they have less opportunity to have them. But some people still suffer from

nightmares as adults.

Some people have a rare disorder in which the brain mechanisms that normally

inhibit the voluntary muscles fail, allowing the person to thrash around and even get up

and act out nightmares. This disorder is called REM behavior disorder (RBD), which is

a fairly serious condition (Nihei et al., 2012; Shafton, 1995). Usually seen in men over age

60, it can happen in younger men and in women. Researchers have found support for

the possibility that the breakdown of neural functioning in RBD may be a warning sign

for future degeneration of neurons, leading to brain diseases such as Alzheimer ’s and

While this infant is sleeping, an increased
amount of REM sleep (occurring about half
of the time she is asleep) allows her brain to
make new neural connections.

Nightmares of being chased by a monster or
a similar frightening creature are common,
especially in childhood.

REM rebound
increased amounts of REM sleep after
being deprived of REM sleep on earlier
nights.

nightmares
bad dreams occurring during REM
sleep.

REM behavior disorder (RBD)
a rare disorder in which the mecha-
nism that blocks the movement of the
voluntary muscles fails, allowing the
person to thrash around and even get
up and act out nightmares.