What do we know about sleep quality?
Research shows that sleep quality is decreasing worldwide. But what does that actually mean?
For anyone who studies late, switches between exam prep and scrolling, or lives with irregular routines, the answer matters: sleeping for many hours is not the same as sleeping well. What determines how alert and focused you feel the next day is not only the length of your sleep, but how your sleep is structured.
One of the most important parts of sleep is REM sleep. This is the stage where the brain processes memories, emotions, and impressions. In other words, exactly what you need when you are learning new things.
The study also highlights how stress, global events, and lifestyle affect sleep. But equally important is the balance between the different sleep stages. To understand what good sleep actually is, we need to look more closely at how sleep works, not only count hours.
The different stages of sleep
Sleep is a complex process made up of several stages, each with its own characteristics and functions. Understanding these stages can help you improve your sleep quality and overall health.
Wakefulness
Before you fall asleep, your brain is active and alert. Your body gradually slows down and prepares for sleep.
Stage 1: Light sleep (transition stage)
This is where you drift from wakefulness into sleep. Your muscles relax and brain activity slows down. This is a very light stage of sleep, and you can be woken up easily.
Stage 2: Core sleep (NREM)
Your body temperature drops, your heart rate slows, and your brain activity becomes calmer, with short bursts of rapid activity called sleep spindles. This stage makes up a large part of the night.
Stage 3: Deep sleep (NREM)
This is the body’s repair mode. Your body recovers, builds muscle, and strengthens the immune system. Brain waves slow down significantly, and it becomes difficult to wake someone up. If you are woken during deep sleep, you may feel confused and disoriented.
REM sleep (dream sleep)
REM stands for Rapid Eye Movement, referring to the quick eye movements that occur during this stage. During REM sleep, the brain is almost as active as it is when you are awake. This is when most dreams occur.
REM sleep is especially important for memory, learning, and creativity, which are all essential during periods of studying.
A typical night includes several sleep cycles of 90 to 120 minutes, and each cycle contains all stages. When these cycles can run uninterrupted, sleep becomes far more restorative.
Does it matter what time we sleep?
Yes, absolutely.
The body is governed by the circadian rhythm, your internal clock that regulates sleep and wakefulness based on light and darkness. Flipping your sleep schedule is similar to constantly living with jet lag.
Melatonin is controlled by light
The sleep hormone melatonin starts being produced when it gets dark, often around 9 to 10 PM. Late nights and strong screen light can slow down this process.
Deep sleep happens early
The most important periods of deep sleep usually occur between 10 PM and 2 AM. Going to bed much later can reduce the most restorative part of sleep.
REM sleep depends on regularity
REM sleep becomes longer towards the morning. Irregular sleep times can disrupt these cycles, which affects memory and concentration.
Your body clock and daylight work together
Sleeping when it is dark and waking when it is light helps the body keep energy levels and mood more stable. Waking up late can make the day feel sluggish from the start.
For most people, sleep between around 10 PM to 6 AM or 11 PM to 7 AM is the most beneficial, especially if the timing stays consistent, even on weekends.
How can we improve sleep?
- Small adjustments can make a big difference.
- Get daylight early in the day
- Limit caffeine and alcohol
- Move your body during the day, but not late in the evening.
- Keep your bedroom cool and dark.
- Use your bed only for sleep
- Eat light in the evening
- Create a calming evening routine
- Listen to your body, and do not lie awake struggling in bed.
Good sleep is like a shortcut to better focus, memory, and wellbeing. For students, it can be the difference between getting through the day and actually having the mental energy to absorb what you are learning.
Small changes in everyday life can go a long way. Start tonight.