An average person spends one-third of their time sleeping. Uninterrupted, quality sleep at night will help you repair different functions in your body. Good sleep will keep your heart healthy and reduce stress.
The sleep cycle is the back and forth transition between the stages of sleep. Having a healthy sleep cycle where the sleeper spends adequate time in each stage is important for both the brain and body functions. Sleep calculators can help you achieve a consistent sleep schedule. To learn more about sleep calculators click here. You can also track your sleep using smartwatches.
Stages of the Sleep Cycle
The stages of the sleep cycle are categorized based on the characteristics of the brain and body. The main characteristics are brain frequencies, eye movements, and muscle movements.
The first three stages are the non-REM sleep, while the last stage is the rapid eye movement (REM) sleep. All four stages play an important role in restoring brain and body functions.
An adult goes through four or five sleep cycles every night. The length of each sleep cycle varies, but most sources indicate the average length is 90 minutes.
It gets difficult to wake the sleeper as they enter the higher stages of non-REM sleep. In Stages 3 and 4, everything in the body is repaired, and new muscle or bone growth occurs. These stages can also help boost immunity.
The body and brain frequency are slower in this stage of sleep compared to wake time. But the body is not fully relaxed. Even the breathing is at the normal rate in this dozing-off stage. Stage 1 sleep is the easiest to wake up from. The brain is still active, and it produces slow brainwaves.
The normal length of this stage is between 1 to 5 minutes. If the person is left undisturbed, they can quickly move to the next stage, especially at night.
This stage is categorized by the sleep spindles and the sawtooth waves. This can be considered as deep sleep as there is less chance of awakening. The breathing and heart rate slow down in this stage as the muscles start relaxing.
The body temperature also decreases, and the eyes stop moving. The length of this stage is between 10 to 60 minutes.
This stage has several names, such as Delta Sleep, Slow Wave Sleep (SWS), and Deep Sleep. The brain produces delta waves in stage 3.
The sleeper experiences the deepest sleep stage of Non REM sleep here. The sleeper is difficult to awake in this stage. This stage is critical for the growth and recovery of the human body.
This deep sleep stage can be 20 to 40 minutes long. The muscles movement, breathing, and heart rate decrease as the body enters this stage. The overall length for stage 3 decreases with age; older people spend more time in stage 2 compared to Slow Wave Sleep.
This stage is the longest in the early cycles, but as the person continues to sleep, more time is spent in stage 4. Stage 3 of the sleep cycle is important to wake up refreshed in the morning.
This is the REM sleep where most sleepers dream. It is also known as paradoxical or active sleep. The breathing is irregular, and the heart rate is elevated in this stage. The eye movement is also fast; hence this stage is named the rapid eye movement.
The brain activity in this stage resembles that of awake time. This stage of the sleep cycle is critical for the cognitive functions of the brain.
Stage 4 sleep can be 10 to 60 minutes long on average. The voluntary muscles in your body are disabled during the last stage of the sleep cycle; hence the movement is restricted.
How Many Hours of Sleep Are Needed Based on Age?
Although sleep is needed for all age groups, the number of hours needed to restore the mind and body will vary. The number of hours will also depend on daily activities, health issues, or sleep patterns. Below is the average number of sleep hours needed for individuals from different age groups.
- Newborn babies (up to 3 months old) need 14 to 17 hours of sleep.
- Infants and toddlers from the age of 4 months to 2 years need 12 to 15 hours of sleep.
- Preschool children that are 3 to 5 years old need 10 to 13 hours of sleep.
- Children from the age of 6 to 13 years need 9 to 11 hours of sleep.
- Teenagers between the age of 14 to 17 years need 8 to 10 hours of sleep.
- Adults from the age of 18 to 64 years need 7 to 9 hours of sleep.
- Adults who are 65 or older than that need 7 to 8 hours of sleep.
Factors That Impact the Sleep Cycle
Sleep Patterns – Having irregular sleep for multiple days can disrupt the normal sleep cycle.
Age – The time spent in each stage of the sleep cycle varies depending on age. As an example, newborns spend more time in REM sleep compared to adults.
Sleep Disorders or Medical Conditions – People with insomnia or sleep apnea struggle with having a proper, healthy sleep cycle.
Alcohol or Drug Consumption – Medicinal drugs and alcohol can change the normal sleep cycle.
Resetting the Sleep Cycle
Sleep cycles can be disturbed by stress, changes in time, traveling, shift works, and health issues. Following are few tips for adjusting your sleep cycle.
- If you want to sleep early to adjust your sleeping routine, only move the sleeping time back by 15 minutes.
- Avoid napping during the day so that your body is tired at night and you can fall asleep earlier.
- Strictly follow the sleep schedule after resetting your bed and wake-up time to avoid disrupting the sleep cycle.
- Exercise regularly but do not exercise or eat right before bedtime.
- If you are planning to travel to a different time zone, shift your bed and wake up time according to the new time a week or two before traveling.
- Create a relaxing sleep environment by adjusting the lights and temperature in the room.
- Have a warm bath before bed to relax your body.
- Avoid caffeine or alcoholic drinks before going to bed