What are sleep cycles?
Over the course of a night's rest, your sleep is made up of one or more cycles of 4 distinct stages of sleep, each with their own defining characteristics. Each stage has a tell-tale combination of brain wave signatures, motor activity levels, and breathing and heart rates. Your body can go through each stage at varying durations to make up an identifiable cycle that typically ranges from 80-120 minutes averaging at 90 minutes. This structural organization of normal sleep is commonly referred to as “sleep architecture”.
What are the stages?
The 4 stages are comprised of 1 rapid eye movement (REM) stage and 3 non rapid eye movement (NREM) stages. They each have a depth, which indicates how difficult it is to wake someone during that stage.
Experts suggest the deeper stages of sleep are critical for overall body restoration, healthy cognitive function, and memory consolidation. Failure to undergo these stages of sleep may explain why we have profound negative consequences in physical and mental health as well as learning.
What's the calculator for?
The aim is to approximate a specific sleep time or wake up time to allow yourself to wake up at a light stage of sleep. It seems helpful to try to avoid interrupting deeper sleep stages. In doing so, you might find yourself able to wake up easier and feel less groggy.