Sleep is a reversible state of decreased awareness of and responsiveness to the environment. Sleep has a number of purposes, such as conservation of energy, restoration of cellular energy stores, regulation of emotion, consolidation of memory, elimination of emotions, brain development, and other numerous different biological functions, such as immune system maintenance.
Sleep consists of two physiological states, such as non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM is again sub-divided into four stages (stage I, II, III & IV). Brain activity patterns are altered in the various stages of sleep. This can be traced by electroencephalogram (EEG).
- Stage I is when sleep begins. The electroencephalogram (EEG), a tracing of electrical activity of the brain, is low voltage with mixed frequencies and decreased alpha activity relative to the state of wakefulness.
- Stage II has more slow activity, sleep spindles and K complexes.
- Stage III has even more slow EEG activity.
- Stage IV is marked by the slowest brain activity.
- Stages III and IV together are referred to as slow-wave sleep (SWS) or delta sleep.
Metabolism of the brain is the highest during the REM stage of sleep with low voltage, mixed frequency, non-alpha EEG. Heart rate, blood pressure, and respiration are variable. Most dreams, including nightmares, happen during REM sleep. Sleep is cyclical. A REM cycle happens every 90 to 100 minutes at night. The initial REM cycle is the shortest, typically less than 10 minutes. Subsequent REM cycles can last 15 to 40 minutes each.
Types of Sleep Disorders
- Sleep disorders can be categorized in various ways. In DSM IV (Diagnostic and Statistical Manual of Mental Disorders IV), sleep disorders are divided into dyssomnias and parasomnias. Dyssomnias are disorders of sleep quantity or timing. Insomnia and hypersomnia are some examples of dyssomnias.
- Parasomnias are sleep or wake abnormal transition behaviours. A third category of sleep disorders is referred to as sleep-wake schedule disturbance (circadian rhythm sleep disorders).
- ICD 10 (International Classification of Diseases 10) has categorized the sleep disorders as Insomnia, Hypersomnia, Circadian rhythm sleep disorders, Sleep related apnea, Narcolepsy and Cataplexy, Parasomnia, Sleep related movement disorders and Sleep disorder not specified.
Clinical Features of Sleep Disorders
Insomnia is a subjective disturbance of the quality or quantity of sleep. It encompasses initiation or maintenance difficulty of sleep.
Insomnia can be subdivided into primary insomnia and secondary insomnia. Primary insomnia is caused by disturbance in the inherent mechanisms by which sleep is controlled. Poor sleep hygiene is a frequent cause of primary insomnia. Psycho-physiological insomnia is a chronic disturbance of sleep induction in which the patient has a tendency to ruminate about things on his or her mind while in bed prior to sleeping. In sleep state misperception (also referred to as subjective insomnia) there is disconnection between the patient's subjective experience of sleeping and the objective measures of sleep (e.g., EEG). In secondary insomnia, the sleep disturbance is secondary to some medical or psychiatric disorder. Sleep disturbance in induction or maintenance can arise in several medical (e.g. painful or uncomfortable illness, sleep apnoea syndromes, nocturnal myoclonus and restless legs syndrome, substance interactions, endocrine or metabolic disease, infectious disease, neoplasm or other disease) and psychiatric disorders (e.g. anxiety, depression, circadian rhythm sleep disorder, posttraumatic stress disorder, schizophrenia).
Hypersomnia is the presence of excessive amounts of sleep, excessive daytime somnolence, or occasionally both. The patient is not refreshed even after the excess sleep. Similar to insomnia, hypersomnia may also be primary or secondary. Primary hypersomnia is referred to as idiopathic hypersomnia. Secondary hypersomnia occurs with different medical illnesses (e.g. Kleine-Levin syndrome, menstrual-associated somnolence, metabolic or toxic illness) and psychiatric illnesses (e.g. alcohol and depressant drugs, withdrawal from psychostimulants, depression).
Periodic limb movement syndrome (PLMS) (also referred to as nocturnal myoclonus) is a dyssomnia that is defined by periodic stereotyped limb movements (most commonly the legs) during sleep. The person is neurologically normal when awake. It is linked with renal disease, iron and vitamin B12 anaemia.
Restless limbs syndrome (RLS) is a painful subjective feeling of the limbs (often legs) that is felt as ants crawling over the skin. It is worse at night and relieved by changing position. RLS occurs in pregnancy, iron or vitamin B12 deficiency anaemia, and renal disease.
Parasomnias consist of nightmare disorder, sleep terror disorder, sleepwalking disorder (somnambulism), sleep talking (somniloquy), REM sleep behaviour disorder and sleep related bruxism. In nightmare disorder, there are vivid dreams that become increasingly more anxiety-provoking. They occur during REM sleep. The person is able to remember these dreams. Sleep terror disorder happens during deep NREM (stages III and IV) sleep. The patients usually sit up in bed with a terrorized look on their face, scream loudly, and sometimes awaken immediately with the feeling of great terror. Yet the next morning there is little, if any, remembrance of the incident.
Narcolepsy is a sleep disorder that presents with excessive daytime sleepiness as well as other features including sleep attacks (an episode of irresistible drowsiness, which results in perhaps 10 to 20 minutes of sleep, after which the patient feels refreshed), cataplexy (sudden weakness of the weight-bearing muscles, lasting less than one minute and occurring in association with the display of emotion, e.g., anger or laughter), sleep paralysis (a short episode of paralysis occurring as the patient falls asleep or in the morning when waking) and hypnagogic hallucinations (prominent dream-like events occurring as the patient falls asleep or is in the act of waking up in the morning). It typically starts in young adulthood and adolescence.
Sleep-wake schedule disturbance disorders (circadian rhythm sleep disorders) are defined by desired and actual sleep time misalignment. These are delayed sleep-phase syndrome (where sleep and wake hours that are later than wished for), advanced Sleep Phase Syndrome (where sleep and wake hours that are earlier than wished for), jet lag type (sleepiness and wakefulness that occur at an unsuitable time of day in relation to local time, following repeated travel over more than one time zone) and shift work sleep disorder (insomnia in the main sleep period or hypersomnolence in the main awake period with night shift work or rotating shift work).
REACH With Solh Wellness
Resilience isn't about surviving—it's about healing. At Solh Wellness, we build Resilience for e.a.c.h. because no struggle should be endured alone. When life presents us with challenges, resilience enables us to progress—not by pushing aside pain, but by Evaluating, Acting, Connecting, and accepting Healing in the process.
In terms of trauma, we all often stuff it, hoping that if we just keep quiet about it, it will go away. But trauma does not simply evaporate—it sticks with us, influencing our thinking, feelings, and relationships. At Solh Wellness, we treat trauma with kindness and whole-person care:
- Evaluate the effects of trauma with self-awareness and empathetic reflection.
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Healing is not forgetting the past; it is drawing strength from your experience. You are not alone. With proper support, resilience, and connection, healing is always an option—one step at a time.
