Health and Wellbeing
What’s the difference between light sleep and deep sleep?
With our increasingly fast-paced world, there’s an obsession with getting a good night’s sleep.
We often talk about the ‘quality’ of our sleep – and usually, we are referring to our deep sleep. However, it’s not just your deep sleep that matters. Even on those nights when you thought you weren’t sleeping deeply, your light sleep was giving you a type of restoration that is absolutely needed for your mental and emotional health.
Key takeaways:
- Not all sleep needs to be deep. Light sleep plays a vital role in mental and emotional restoration.
- Deep sleep supports physical recovery, immunity, and overall health.
- A balanced mix of light, deep, and REM sleep is what truly defines good sleep quality.
What are the different stages of sleep?
Everyone has a unique relationship with sleep, with the structure responding to your needs.
The ‘architecture’ of sleep involves five distinct stages, including light sleep, deep (or slow wave) sleep, and REM sleep.
Understanding light, deep and REM sleep
We sleep in roughly 90-to-110-minute phases. During this time, your body has several complex biochemical, hormonal and physiological changes. One phase consists of five layers comprising:
- Two stages of light sleep (Stages 1 & 2)
- Two stages of slow wave or deep sleep (Stages 3 & 4)
- One stage of Rapid Eye Movement or REM sleep (Stage 5)
We move through every stage multiple times every night, and each supports your health differently.
As we get older, a good night’s sleep is essential – discover more in my previous blog.
What is ‘light sleep’ and what happens during it?
The ‘warm-up’ for good deep sleep, most of the night is spent in stages 1 and 2. The body relaxes, heart rate slows, and the brain begins to consolidate and file memories and information from the day. Light sleep tends to be easier to wake from.
What is deep sleep, and why does it matter?
Brain wave activity slows down in stages 3 and 4, allowing for deep sleep.
The body produces hormones and neurochemicals that bring about physical repair and restoration. This helps to bolster the immune system and rebalance the hormonal system.
What is REM sleep, and why do we need it?
At the end of each 90-minute stage comes a 10–15-minute burst of REM sleep. During this phase of sleep, our sleep depth becomes shallower, and we can even drift into a state of semi-consciousness called a hypnagogic trance.
During REM sleep, we experience two types of dreams:
- Processing dreams: For memory consolidation
- Emotional dreams: Related to creativity, problem solving, healing trauma and emotional stress
What’s the difference between light sleep and deep sleep?
Getting enough light and deep sleep is equally important for your health, but for different reasons.
Discover the key differences between deep and light sleep in my handy comparison table below:
| Light sleep | Deep sleep |
| Greater brain activity | Slower brain activity |
| Easier to wake | Harder to wake |
| Mental and emotional restoration | Physical repair and restoration |
| Transition into deep sleep | Immune function and hormone balance |
How much light sleep and deep sleep is normal?
If you’re wondering how much deep and light sleep you need, here’s what is generally considered normal for adults, roughly aged 20–60:
| Light sleep | 45–60% | 3.5–5 hours |
| Deep sleep | 13–23% | 1–2 hours |
| REM sleep | 20–25% | 1.5–2 hours |
As you get older, your deep sleep may decrease by around 1-2% per decade and become lighter. This is because structural changes in the brain begin to occur, and we start to produce less melatonin and growth hormone.
Many physical health and mental health conditions also reduce deep sleep and increase the need for REM sleep.
Due to hormonal, biological and social factors, women may also need more sleep. You can explore this topic more in my latest article.
Final thoughts
From the mental restoration that light sleep brings to the physical benefits of deep sleep, all sleep stages matter equally when it comes to getting a good night’s sleep.
Over here at Oak Tree Mobility, we’re on a mission to help you get the restoration you deserve, so don’t forget to check out our adjustable beds to encourage an optimal sleep cycle.
Explore our adjustable beds
Frequently asked questions:
How do I increase my amount of deep sleep?
Many of my clients ask me, “How do I increase my REM and deep sleep?” It all comes down to maintaining good habits and a healthy lifestyle. Discover my five non-negotiables as a starting point for increasing your deep sleep.
Are sleep trackers helpful?
They can be helpful, but the data needs to be taken with a pinch of salt. At the end of the day, the only way to accurately know what’s going on with your sleep is to have a polysomnography test at a sleep clinic.
Should I be worried if my tracker shows very little deep sleep?
If your tracker shows a low sleep score, and you’re tired, then you probably need to work on improving the quality of your rest.
Why does my deep sleep change from night to night?
Many factors can affect your sleep from one day to the next – caffeine and alcohol, eating too soon, bedtime, stress, or not drinking enough water.
Why do I get more light sleep than deep sleep?
Ask yourself, am I more stressed than usual? Am I spending too much time on my electronic devices? Am I feeling off-balance physically, mentally or emotionally? These can all impact the amount of deep sleep.
Do light, deep, and REM sleep happen in order?
We sleep in 90–110-minute cycles, generally in the order of light, deep, and REM sleep. Sometimes REM can occur at the start of our sleep, especially if we are stressed, or our brain is filled with information from the day.
How can chasing ‘deep sleep’ backfire?
Chasing deep sleep can make us unnecessarily sleep aware and almost fixated on trying too hard to sleep well. Remember, light sleep is just as important as deep sleep.
Can you function well without enough REM or deep sleep?
No, both REM and deep sleep are vital for our mental, emotional and physical health.
Does going to bed earlier increase deep sleep?
Yes, going to bed earlier can help. Research indicates that going to bed around 9.30pm to 10pm can set you up for deeper, more restorative sleep.
Can naps affect deep sleep at night?
It can if done for the right duration and at the right time of day. Napping can impact your sleep negatively.
Can pain or mobility problems affect deep sleep?
Absolutely. Deep sleep can decrease, and sleep becomes more irregular with increased awakenings.
When to seek sleep support?
If your sleep problem lasts more than three to four weeks and affects your quality of life, energy levels and daytime functioning, it might be time to seek help.
Further Reading & Sources
- https://www.weljii.com/blog/light-sleep-vs-deep-sleep-whats-the-difference/
- https://www.slumberpod.com/blogs/our-blog/light-sleep-vs-deep-sleep
- https://www.eightsleep.com/blog/the-difference-between-light-and-deep-sleep-how-much-do-you-really-need
- https://www.calm.com/blog/rem-sleep-vs-deep-sleep
- https://oaktreemobility.co.uk/help-and-advice/health-and-wellbeing/sleeping-alone-vs-a-partner-which-is-better
