Why Do We Sleep? Unpacking the Science behind Rest

For as important as sleep is, we know shockingly little about it. Sleep remains one of the largest mysteries in all of neuroscience. Despite its commonality and our breakthroughs in sleep health, we know little about why we need it — or why some people need less of it to function in the same way others do.

Here’s what we do know: sleep is vitally important in supporting physical health, from your digestive system to your heartbeat. And it’s made of several stages, regulated by your circadian rhythm in ways that allow your body to grow, heal, and restore its energy levels.

Sleep Stages and your Circadian Rhythm

Your sleep is divided into stages. There are two main stages to sleep: Rapid Eye Movement (REM) and non-REM sleep. These stages cycle multiple times as you sleep.

Non-REM sleep is broken into three stages:

Stage 1: Light sleep where you can be easily awakened. Muscle activity decreases but your eye movements remain slow.
Stage 2: A deeper level of sleep with a reduced body temperature and heart rate. Breathing also slows in this stage.
Stage 3: Deep sleep when it’s most challenging to wake someone.

REM sleep is otherwise known as deep or slow-wave sleep, which is when most dreaming occurs. During REM sleep, your brain remains highly active. Your eyes move rapidly and your body suppresses muscle activity, keeping you from acting out your dreams. This is the stage of sleep where physical healing typically occurs, alongside immune system support.

A complete sleep cycle typically lasts about 90 minutes. It includes all sleep stages, beginning with Stage 1 of non-REM sleep and culminating with REM sleep. As the night progresses, the time you spend in deep sleep and REM sleep increases.

Your entire sleep-wake cycle, whether you’re in REM sleep or an active state during the day, is regulated by your circadian rhythm. This is your internal, natural clock that follows a roughly 24-hour cycle, helping your body achieve wakefulness and sleep when appropriate. Various factors, including a sleep disorder or an overnight work schedule, can hinder or completely compromise your circadian rhythm.

Why Do I Need Sleep?

Even if scientists don’t understand exactly what causes sleep, they understand many of the key benefits that sleep offers the body. Sleep helps improve your mood, brain functionality, and various other aspects of your physical health.

Here are a few of the most important things sleep can do for you:

Rest and restoration: Sleep allows your body to recover from the day’s activities. Whether that means healing from physical scrapes or rejuvenating your internal systems, recovery is a central process of sleep.
Energy conservation: Sleep helps reduce your energy expenditure, replenish your energy reserves, and prepare you for the next day’s events.
Memory consolidation: During the various stages of sleep, your brain will process and store memories. This helps retain and reinforce what you’ve learned and experienced during the day.
Emotional regulation: Sleep plays a significant role in regulating emotions and mental health. Poor sleep can lead to irritability and mood swings, while sleep allows your body and brain to make sense of the emotions you feel and process.
Immune system support: Sleep is essential for a healthy immune system. During sleep, your body will produce cytokines — proteins that help regulate your immune response. A lack of sleep can weaken your immune system’s ability to defend against infection.
Hormone regulation: Sleep is closely related to the way your body regulates hormones. Specifically, the sleep-wake cycle influences the way your body releases hormones like melatonin and cortisol.

Scientists still don’t understand the exact reasons why we need sleep. However, it’s clear that sleep helps your body consolidate memories, restore energy levels, and support immune system functionality. Getting enough sleep allows your body to follow a healthy sleep pattern, properly regulate sleep and wake periods, and protect mental health.

How Can I Protect the Quality of My Sleep?

Protecting the quality of your sleep is one of the smartest health investments you can make. Poor sleep can lead to a range of health issues. To improve and maintain the quality of your sleep,. Consider implementing the following sleep hygiene practices:

Stick to a consistent sleep schedule: Go to bed and wake up at the same time each day. If this is difficult to achieve, try tracking your sleep with a sleep app or sleep journal to learn the wake and sleep times your body prefers.
Create a relaxing sleep routine: Develop a calming pre-sleep routine to remind your body when it’s time to begin winding down for the day. Consider activities like reading, taking a bath, listening to calming music, or meditating as part of your sleep routine.
Optimize your sleep environment: Make your room more conducive to sleep by preserving a comfortable temperature and dimming lights. If possible, reserve your bedroom for sleep and intimacy only.
Limit screen time before bed: Especially in the 60 minutes before bed, avoid electronics and the blue light they emit. Blue light can interfere with your sleep-wake cycle and throw off your circadian rhythm.
Watch your diet: Avoid caffeine, alcohol, and other substances that create an unhealthy diet. Instead, prioritize nutrient-dense foods and ingredients that your body can easily digest.
Get regular exercise: Regular physical activity can help your body achieve better sleep. Aim for at least 30 minutes of exercise each day, and try to finish workouts during the afternoon to give your body a chance to recover before bed.
Manage stress levels: High stress levels can lead to poor sleep quality. Practice stress-relieving techniques like mindfulness to calm your mind before bed.
Limit naps: Short naps can be refreshing, but naps longer than 30 minutes can make it more difficult to fall asleep at night. If you need to nap, keep it under a half-hour and avoid napping late in the day.

Remember that improving your sleep quality can take time and experimentation. What works well for some people won’t work well for others. For best results, be patient and adaptable in your approach to protecting your sleep. Incorporate sleep hygiene best practices into your daily routine to enjoy the best benefits of restorative rest.

Sleep is also more enjoyable when you’re using the right mattress — and that’s where Mattress Warehouse can help. Our bedMATCH sleep diagnostic program analyzes your complete sleep profile, from your height and weight to your preferred sleep position, to identify the best mattress options for you. In five minutes, you’ll have a complete list of mattresses at every price point that are made for sleepers like you.

Don’t worry if you can’t experience bedMATCH at a Mattress Warehouse near you. Take the online version of the bedMATCH sleep diagnostic quiz to browse high-quality mattress options right now.