heräämisvaiheen

Heräämisvaihe refers to the initial stage of sleep, known scientifically as Stage N1 or NREM Stage 1. This is the lightest phase of sleep, transitioning from wakefulness to deeper sleep. During heräämisvaihe, brainwave activity begins to slow down from the faster patterns observed during wakefulness. Muscle activity decreases, and the body may experience involuntary muscle twitches known as hypnic jerks.

Individuals in heräämisvaihe can often be easily awakened and may not even realize they were asleep, sometimes describing it as feeling like they were just dozing. This stage typically lasts for only a few minutes, usually between 1 and 5 minutes, before progressing into the next stage of non-REM sleep. It is characterized by a decrease in heart rate and breathing rate, although these remain relatively stable.

Heräämisvaihe is a crucial part of the sleep cycle, serving as the gateway to more restorative stages of sleep. While it doesn't offer the deep physical and mental restoration of later sleep stages, its presence is necessary for the overall progression through the sleep architecture. Disruptions to this initial phase can affect the quality and continuity of sleep.