A good night’s sleep is important for both the body and brain. Celebrate World Sleep Day by understanding the four stages of sleep and how to get more restful z’s.
Stage 1: Transitional sleep
The sleep cycle begins with the shortest stage of sleep. The light sleep stage accounts for just 5% of our overall sleep each night.
“Light sleep is when you’re transitioning, either when you are falling asleep or just before you wake up,” said Brandy J. McKelvy, MD, a pulmonologist with UT Physicians Internal Medicine — Texas Medical Center.
Stage 2: Light sleep
Most sleep happens at a midrange level, right before deep sleep.
“This stage is important for memory, learning, and overall health,” said McKelvy, a professor in the Division of Pulmonary, Critical Care, and Sleep Medicine at McGovern Medical School at UTHealth Houston. “This should account for about 45% of a good night’s rest.”
Stage 3: Deeper sleep
The most relaxing stage of sleep is called deep sleep.
“This is the hardest stage to wake up from,” said McKelvy. “Deep sleep is when your brain powers down. Your mind and body will be in a relaxed state with very limited movement.”
Deep sleep is the restorative stage of sleep. During this stage the body undergoes tissue repair, the immune system is strengthening, and human growth hormone is released.
“For kids, this stage of sleep is especially important,” said McKelvy.
Deep sleep accounts for 25% of the total sleep cycle.
Stage 4: Rapid Eye Movement (REM)
Often referred to as the REM cycle, this stage of sleep is when the brain turns back on.
“This is when dreams happen because the brain is active. The body is paralyzed, except for the eyes and the diaphragm for breathing,” said McKelvy. “In the sleep lab, we can always tell when someone is going through REM sleep because we can see it in their eye movements.”
During this stage, the body’s energy is focused on the brain, allowing it to create new connections.
“These connections, also called synapses, are when the brain cells communicate,” explained McKelvy. “This is how the brain recovers, and you incorporate memories.”
REM sleep is the final 25% of the sleep cycle.
“More of REM sleep happens closer to the morning, and that’s why some people will remember their dreams because they’re dreaming right before they wake up,” said McKelvy.
Tips for good sleep hygiene
Optimal sleep is seven to eight hours without interruption. Follow these tips to make your sleep better, more efficient, and healthier:
- Go to bed and wake up at the same time every day, no matter what day of the week.
- Reserve the bed for sleep. Do not watch TV, work on the computer, or scroll through your phone while in bed.
- Keep the bedroom dark, cool, and quiet.
- Avoid drinking caffeine within 10 hours of bedtime.
- Avoid eating or drinking within three hours of bedtime.
- Stop working within two hours of bedtime.
- Avoid using an electronic device within one hour of bedtime.
- Avoid using the snooze button when waking up.
- Adults should avoid naps. If you have to nap, limit it to 30 minutes.
When to have your sleep checked
“When getting good, uninterrupted sleep, most people will cycle through the four stages of sleep three or four times a night,” explained McKelvy.
If you wake up feeling unrefreshed, it’s likely you did not reach deep sleep or REM sleep.
“Disrupted or insufficient sleep can be harmful to your health,” said McKelvy. “If this is occurring, you should be checked for a sleep disorder.”
Visit our UT Physicians Sleep Medicine specialists to learn more about relieving sleep disorders.
