Levähdysjakso

Levähdysjakso, also known as a sleep cycle or sleep period, is a sequence of stages that the human body goes through during sleep. Each cycle typically lasts about 90 to 110 minutes and consists of four stages: N1, N2, N3, and REM (Rapid Eye Movement). The first three stages are collectively referred to as non-rapid eye movement (NREM) sleep. The stages of a sleep cycle are not fixed and can vary in duration and order throughout the night.

N1 is the first stage of sleep and is often referred to as the transition from wakefulness to sleep. It is characterized by a slowing of brain activity and a reduction in muscle tone. N2 follows N1 and is the stage where most of our sleep occurs. It is marked by the presence of sleep spindles and K-complexes, which are bursts of brain activity. N3, also known as deep sleep, is the stage where we experience the most restorative sleep. It is characterized by slow brain waves and is crucial for physical recovery and memory consolidation.

REM sleep is the final stage of the sleep cycle and is characterized by rapid eye movements, increased brain activity, and vivid dreaming. It is essential for emotional regulation, learning, and memory consolidation. The number of REM cycles increases throughout the night, with the longest REM period occurring in the last third of the night.

Sleep cycles are not continuous but occur in a repeating pattern throughout the night. The number of cycles can vary depending on the individual's age and overall sleep duration. For adults, a typical night of sleep consists of 4-6 complete sleep cycles. Children and adolescents may have more cycles due to their longer sleep duration. Understanding the stages and cycles of sleep can help individuals optimize their sleep patterns and improve overall sleep quality.