What is a Sleep Cycle?

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Are you a light sleeper? Were there times when you heard a noise or someone walked into the room and you suddenly woke up? It can be frustrating and confusing, especially when you feel more tired upon waking up.

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You may experience days when you snooze your alarm numerous times. You have struggled to get up and had to drag yourself out of bed. If both of these sound like you, then it may have to do with the stage of sleep that you were in prior to waking up. 

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The sleep cycle refers to our biological rhythm. Our body clock sets our internal functions like changes in blood pressure, metabolism, and body temperature. It is the 24-hour cycle that is linked to daylight and darkness. The sleep cycle has four stages.

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The Sleep Stages

Scientists divide the sleep cycle and sleep stages into two major categories: REM (Rapid Eye Movement) and NREM (Non-Rapid Eye Movement). 

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Under NREM sleep, there are three separate stages. The amount of sleep occurring during these stages varies throughout a person’s life. 

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Sleep usually begins with an NREM stage and is followed by the REM period. The complete sleep cycle usually ranges from 70 to 120 minutes, and generally, there are three to four cycles of sleep every night. Each stage affects the brain in different ways.

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Learning more about the sleep cycle can help you manage your sleeping habits. Here is a more detailed look at the various stages in a sleep cycle:

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The First NREM Stage (Stage 1): The stage during which you fall asleep.

As you close your eyes, your mind starts to grow quiet. Though you may feel yourself drifting off to sleep, small disturbances can easily awaken you during this stage.

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This stage is the first and lightest phase of NREM sleep. In this stage, your muscles start to release the tension and relax. Slow eye movements are also present, and your breathing slows down. Scientists consider this stage a transitional period between being awake and asleep. 

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When it comes to your brain activity, it produces both low frequency and high amplitude alpha and theta waves. In simpler terms, stage 1 results in brain activity similar to a relaxed and awake person. Stage 1 usually occurs within five to ten minutes of falling asleep.

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The Second NREM Stage (Stage 2): The first stage of genuine sleep - light sleep.

It's quite difficult to stay awake during this stage. Your body temperature and heart rate drop, and brain activity and muscle movement decrease. Stage 2 usually takes around 20 minutes to happen. This is an important sleep stage for memory creation and retention.

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The Last NREM Stage (Stage 3): The occurrence of deep sleep. 

Waking up from deep sleep might leave you confused and disoriented. This stage is where you will start to experience deep sleep. Stage 3 is considered a "low wave sleep" period. Very low-frequency delta waves predominate in your brain. This step happens 35 to 45 minutes after falling asleep.

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At this point, your blood pressure drops further. You also experience deeper breathing, and muscle movements are absent. Specific hormones are released at this stage. Some hormones trigger the growth and replenishment of muscles, as well as those that control your appetite and boost your immune system.

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Sleep talking, sleepwalking, and night terrors can also be found in stage 3. 

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REM Sleep (Stage 4):  The dreaming stage.

As its name suggests, this stage refers to the time wherein rapid eye movement occurs. Intense dreaming happens during REM, characterized by heightened cerebral activity. Your brain activity during this period resembles that of someone awake and, as a result, revitalizes your brain and body.

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REM is a paradoxical stage of sleep wherein as much as there is high brain activity, there is a low muscle tone. During REM sleep your muscles and limbs experience temporary paralysis. This restriction of movement inhibits your body from acting out your dreams at sleep and possibly harming yourself in the real world. 

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If you wake up from the REM stage, you will feel groggy and tired. This stage usually takes place 90 minutes after falling asleep. How long you experience REM sleep varies for each cycle, varying from 10 minutes to almost an hour. 

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After REM sleep, the body usually returns to NREM stage 2 before starting the cycle again. People have varied sleep architecture. The exact cycles and stages one experiences in a night is different for everyone. Some have a smooth and easy rest, while others may experience disrupted sleep. 

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Factors that Affect Sleep Stages

When you experience discontinued sleep throughout the night, this means that you have a disrupted sleep cycle.

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Several issues can be linked to why you experience disruptive sleep cycles. Some of these factors include:

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Age:  As you grow older, sleep becomes lighter, and you get awoken more easily.

Nocturia: This is a condition wherein you frequently wake up with the need to urinate.

Sleep Disorders: Insomnia, sleep apnea, restless leg syndrome, and other disorders can affect your sleep quality.

Lifestyle habits: Sedentary lifestyle and excessive caffeine and alcohol intake can negatively impact your natural progression through sleep stages.

Psychological disorders: Depression and anxiety can keep you up at night.

Pain: Difficulty falling or staying asleep due to acute or chronic pain conditions can limit the restoration experience in a completed and balanced sleep cycle.

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Whenever you experience difficulty falling asleep or staying asleep at night, your sleep cycle will be affected.

Have a Healthier Sleep Cycle

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If you encounter sleeplessness, it's important to understand why and take note of ways to improve your future sleep. With your overall health at stake, remaining positive and making gradual changes is key to attaining a better night's sleep.

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Finding a quality mattress that fits your needs and properly supports your body will help you sleep better through the night. The Restorative Bed™ uses Bryte’s Restorative Sleep Technology platform to power the future of sleep.  Bryte's in-bed technology measures, learns, tests, and applies what each sleeper needs to optimize their restorative sleep through real-time control of temperature, pressure points, and more. Bryte's Rebalancing™ system is a breakthrough technology that senses pressure imbalances as they happen and silently adjusts in real-time to deliver the perfect support for any person in any sleeping position.

Sensors embedded in the bed can help detect your heart and respiratory rate and motion to track your sleep stages. 

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The Restorative Bed™ uses science-backed technology to help you achieve restorative sleep by helping you fall asleep faster, stay asleep longer, and wake feeling more restored. Bryte’s purpose-built software can help you analyze your sleep quality as well. Check out our mattresses and get the sleep you deserve every night. For more information, visit Bryte.com.