Sleep-Wake Disorders

The clinical exploration of psychological disorders continues with another basic need: sleep. What is sleep? What does the REM phase mean? Why do we sleep? I'll try to answer these questions in my own words.

There are many definitions of sleep, but we can identify two key concepts that, intuitively, everyone knows:

1. During sleep, we are unaware of the surrounding reality.
2. Sleep is an essential need.

These statements are easy to verify. While sleeping, we are disconnected from reality, and a lack of sleep has repercussions during wakefulness.

Another well-known fact about sleep is the term "REM" or more specifically, the REM phase. Let’s break this down:

Sleep is divided into cycles that alternate. Each cycle consists of two main stages:

1. Non-REM phase
2. REM phase

During the night, 4 to 5 cycles occur before waking up.

The term REM is an acronym for "rapid eye movement." This means that if you lifted the eyelids of someone in the REM phase, you would see their eyes moving rapidly from side to side.

This stage is characterized by "light" sleep; if awakened during REM, the individual would be oriented to reality. Dreams occur specifically during the REM phase.

On the other hand, the non-REM phase (which is itself divided into sub-stages) includes "deep" sleep. Waking up during this phase often leaves the person feeling groggy and disoriented.

There are various theories about why we sleep, each requiring deeper exploration. However, what is evident is that sleep provides both physiological and psychological benefits, such as:

• Promoting heart health and proper functioning of the immune system
• Maintaining a healthy weight
• Relieving stress
• Improving mood

Conversely, sleep deprivation has numerous negative effects, two of which are daytime drowsiness and irritability.

This is why, at the clinical level, it becomes important to define cases where sleep deprivation causes significant distress, to the point that it can be classified as a psychological disorder.

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) identifies various Sleep-Wake Disorders, including:

1. Insomnia Disorder
2. Hypersomnolence Disorder
3. Narcolepsy
4. The category of Sleep-Related Breathing Disorders, which includes:
   • Obstructive Sleep Apnea/Hypopnea
   • Central Sleep Apnea
   • Sleep-Related Hypoventilation
5. Circadian Rhythm Sleep-Wake Disorders
6. Parasomnias, which include:
   • Non-REM Sleep Arousal Disorders
   • Nightmare Disorder
   • REM Sleep Behavior Disorder
   • Restless Legs Syndrome

Sources

• American Psychiatric Association (2013) - Diagnostic and Statistical Manual of Mental Disorders (5th ed.).
• Bernhill, J. W. (2014) - DSM-5 Clinical Cases.

If you'd like me to describe another psychology topic in my own words, feel free to let me know in the comments!