4 Stages of Sleep
Updated: Feb 10
For some of us, it’s a welcome respite at the end of the day; and for others, it’s a nightly struggle to get the rest we need. According to National Geographic’s most recent article on sleep, 80 million American adults are sleep deprived, meaning they sleep less that 6 hours each night. Being sleep deprived may lead to increased risk of depression, anxiety, psychosis, and stroke.
More and more information is coming out about the importance of sleep and the different cycles of sleep that we experience in a night. Researchers have identified 4 stages of sleep, each characterized by the different brain waves produced while we sleep. Below is a little more information on each stage:
Shallow Sleep—Stage 1 and 2
Stage 1. Typically lasting 5-10 minutes each cycle, in stage 1 the brain stops responding to outward distractions and starts your neurons firing rapidly, working to begin cell repair and improve memory.
Stage 2. The brain waves produced in stage 2 sleep are known as “spindles,” which come from the cerebral cortex. Stage 2 sleep is where we spend up to 50% of our sleeping time each cycle. The spindles work to help turn our short term thoughts and experiences into long term memories. There’s also some indications that the number of spindles produced at night may be an indication of overall intelligence and the ability to perform better on new tasks.
Deep Sleep—Stage 3 and 4
Stage 3. In stage 3, brain waves become longer are are known as Delta waves. In this stage, your body begins to service your bones and muscles; it’s when growth hormone is produced, your immune system is boosted; it regulates both your body temperature and your blood pressure; helps to regulate your mood; and works to repair injuries.
Stage 4. Your brain continues to produce the long Delta waves in stage 4 sleep. Relatively little is known about the differences between stage 3 and 4 sleep, other than in stage 4 sleep, your brain produces Delta waves more frequently. You sleep like you are in a coma: muscles are fully relaxed and brain activity is minimal. Adults typically only spend about 30 minutes in stage 4 sleep, but it is thought that it is necessary for feeling refreshed when we wake in the morning and for helping the brain prepare for the new information it will take in when it wakes. If we don’t get enough stage 4 sleep, we may feel groggy or disoriented when we wake up.
Each of us has our own unique patterns of how often we stay in these sleep stages based on our internal sleep clock. Understanding these stages and how they affect the way we learn and their ties to our overall health is becoming increasingly important in our stress-driven, sleep deprived lives.
Take care and get some sleep!