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How many of you have an activity tracking watch or bracelet that tracks your sleep but have never considered what it might actually be telling you about your sleeping habits? And how you can use the sleep tracking to lose weight and get healthier?

One of the participants in my weight loss group has been using a fitbit to monitor her activity and sleep. She asked me ‘How much deep sleep should I be getting?”, and it occurred to me that merely collecting data isn’t enough. We need to understand and use that data to improve our health.


The Stages of Sleep

Sleep is divided into REM (Rapid Eye Movement) and non-REM sleep. You might have heard of this already. REM is the stage of sleep when you dream and your eyes move, hence the name. Non-REM has three phases. Stage 1 and Stage 2 are light sleep, and Stage 3 is deep sleep. But what does that mean for you?

Stage 1 Sleep

Not particularly restful. This is when you can be easily awakened and you are often aware of what’s going on around you. You stay in this stage very briefly.

Stage 2 Sleep

This is the time when your body processes memories and emotions and our metabolism regulates itself. You spend a lot of time here, and it’s an important period of sleep.

Stage 3 Sleep

Deep sleep is very restorative. It’s when the human growth hormone is released, which repairs tissues. The immune system is boosted, new memories are consolidated and long-term memories are created.


REM Sleep

During this stage, you clear the brain of things you don’t need. Emotion and memory rely on this happening. Think of it like clearing out your memory, like you would on your phone, to allow you to store and process more information thereafter.

You will often have vivid dreams in this stage, and if you awaken just after this stage, you can often clearly remember your dream. As the night continues, you spend more and more time in this stage.

Too little REM sleep can leave you feeling groggy and unable to focus.


Sleep Cycles

We typically go through these stages in four to five cycles of differing lengths throughout the night. The first cycle is around 90 minutes, and subsequent cycles can last between 100 and 120 minutes. They tend to look like this:

Stage 1 => Stage 2 => Stage 3 (Deep) => REM => Stage 1 => Stage 2 …

We spend the first half of the night getting more deep sleep and the second half getting more REM. So what does this mean for you? Well, if you are going to bed at a decent time, you’ll tend to fall into deep sleep from around 11pm to 2 am, and then REM sleep from 3am to 6am.


How Much Sleep do we Need?

The consensus is that you should be aiming for around 15 – 20% deep sleep (ideally 20%), 25% REM and the rest light sleep.

If you go to bed late, then REM is likely the most disturbed, as the body prioritises deep sleep. That means that if you go to bed late, you won’t get enough REM, which can leave you groggy and unable to focus the next day.

Stress, alcohol and some drugs can affect how much deep sleep you get, which means you spend too much time in REM sleep. That too will leave you feeling tired the next day. Too little deep sleep can also have an effect on how your body reacts to insulin.


Sleep and Hormones

Melatonin is a hormone that regulates the wake-sleep cycles. Cortisol is the body’s ‘stress hormone’. Insulin removes glucose from the blood and puts it in your body cells to use as energy or store as fat.

Melatonin is secreted from around 9pm as our eyes and brain register lower light levels. It is at its highest levels between 11pm and 2am, which correspond to the deep sleep stage. At this point, melatonin levels start to drop and cortisol starts being produced. Towards 6am, cortisol peaks, which is what awakens us in the morning.

Blood sugar levels surge when you are sleeping. In a healthy body, insulin can handle this surge by telling the cells of the muscle, fat and liver to absorb the sugar from the blood.  The reason for this is to stop blood sugar levels dropping to a dangerously low level while you sleep and to give you the energy to get out of bed in the morning.


Insulin Sensitivity and Resistance

Think of insulin as the key in the lock, to allow glucose entry in your body cells. When everything is working as it should be, we say you are insulin sensitive. The key is turning in the lock and there is no need to worry.

Insulin resistant means that the key isn’t turning in the lock. Insulin redirects the excess glucose to fat cells and stores it there.

You may be wondering what rabbit hole I have led you down, but I promise, I’m bringing it back around to your fitbit!


Insulin Resistance and Obesity

For years, scientists have been debating the link between insulin and obesity. Which came first? In recent years, the consensus seems to be going in the direction of it being a bit of a vicious circle. Obesity causes insulin resistance. Insulin resistance causes obesity. And on it goes!

Well, scientists have discovered a link between the amount of sleep you get and the release of hormones in your body. Lack of sleep muddles the release of hormones, which messes with your metabolism.

When you don’t get enough sleep, you are more likely to develop insulin resistance. In one study, participants experienced as much as 44% reduction in insulin sensitivity in just one week.

Getting a good night’s sleep isn’t just about feeling refreshed the next day. It could also really help you lose weight.


Lack of Sleep and Weight Gain

In addition to the issue of insulin resistance, when you are tired during the day, it’s a lot harder to avoid giving into easy food, which tends to be unhealthy food. If you are tired, you’ll be less likely to be organised and prepare healthy choices for snacking.


What Do I do Now? 

Here’s the good news. You now know that needing 7 – 8 hours sleep isn’t just an old wives’ tale. It’s science!

In my next post, I’ll go more into the lifestyle habits that lead many of us to this point, and which steps you can take to turn things around. For now, start by checking your sleep tracker and looking more closely at the data it is gathering.

How much sleep are you getting? How much deep sleep? And how much REM?

Try going to bed earlier for a few days and see if you notice a difference. It’s a good idea to take a quick note in your diary of how you were feeling, so you can check if getting more sleep makes you feel better in other ways. Does it help with cravings or your energy levels?

And if you are struggling with your weight or your sleep, why not book a free 30 minute call with me to find out how I can help you? Just click here: