Parasomnias are a group of sleep disorders characterised by abnormal behaviours, movements, or experiences that occur during sleep. These events can disrupt sleep and may result in confusion or distress upon awakening. 

1. Sleepwalking (Somnambulism): Sleepwalking involves engaging in complex behaviours while in a sleep state. People who sleepwalk may sit up, walk around, or perform activities as if awake, even though they are asleep. Sleepwalking typically occurs during deep non-rapid eye movement (NREM) sleep and can range from mild to more complex actions.

2. Night Terrors (Sleep Terrors): Night terrors are intense episodes of fear or terror that occur during sleep. They usually involve screaming, intense distress, and physical signs of fear. Night terrors are most common in children and can cause confusion and disorientation upon awakening.

3. Sleep Talking (Somniloquy): Sleep talking refers to the utterance of speech or vocalizations during sleep. The speech may be coherent or incoherent and can range from simple sounds to complete sentences. Sleep talking is relatively common and often benign.

4. REM Sleep Behaviour Disorder (RBD): RBD involves acting out vivid, often violent, dreams during rapid eye movement (REM) sleep. Unlike normal muscle paralysis during REM sleep, individuals with RBD have the ability to move and may exhibit behaviours such as punching, kicking, or shouting during sleep.

5. Sleep-Related Eating Disorder (SRED): SRED is characterised by consuming food or drink during sleep, often in excessive amounts. People with SRED may have no recollection of these episodes upon waking.

Parasomnias can have various causes, including genetics, sleep deprivation, stress, certain medications, and other underlying sleep disorders. Management of parasomnias depends on the specific type and its impact on an individual's well-being.