sleep-wake disorder

• REM sleep, during which the majority of typical story-like dreams occur, occupies about 20%-25% of total sleep
• NREM sleep stage 1 (N1) is a transition from wakefulness to sleep and occupies about 5% of time spent asleep in healthy adults.
• NREM stage 2 (N2), which is characterized by specific electroencephalographic waveforms (sleep spindles and K complexes), occupies about 50% of time spent asleep.
• NREM sleep stage 3 (N3) also known as low-wave sleep, is the deepest level of sleep and occupies about 20% of sleep time in healthy, younger adults.
• Polysomnography is the monitoring of multiple electrophysiological parameters during sleep.
• Sleep continuity refers to the overall balance of sleep and wakefulness during a night of sleep.
• "Better" sleep continuity indicates consolidated sleep with little wakefulness or fragmentation.
• "Worse" sleep continuity indicates disrupted sleep with more wakefulness and fragmentation.
• Sleep latency refers to the amount of time required to fall asleep (expressed in minutes)
• Wake after sleep onset refers to the amount of awake time between initial sleep onset and final awakening (expressed in minutes)
• Sleep architecture refers to the amount of distribution of specific sleep stages.
• Insomnia Disorder characterized by a predominant complaint of dissatisfaction with sleep quantity or quality, associated with one (or more) of the following symptoms: difficulty initiating sleep, difficulty maintaining sleep, waking up too early, waking up too late, or waking up feeling tired.
• In insomnia the sleep difficulty must occurs at least 3 nights per week and is present for at least 3 months.
• Specifiers for Insomnia:

  Episodic: Symptoms last at least 1 month but less than 3 months.

  Persistent: Symptoms last 3 months or longer

  Recurrent: Two (or more) episodes within the space of 1 year