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“I can’t remember when I last had a good night’s sleep. It was probably some time back when I was in high school.”

This comment came from a Mum in her late thirties. We had been having a general chat about work, children, sleep and the impact of technology.

But if you can’t remember what a good night’s sleep feels like, what does that imply for your ability to think, learn and remember? How does lack of sleep affect your mood, your mental wellbeing, cognitive and physical health?

We all need sleep. It impacts every cell and system in our body. Without sufficient good quality uninterrupted sleep, we pay a huge cost to how well we function and live.

How much is enough?

We spend roughly 1/3 of our lives asleep. Far from being a waste of time, it’s critical to the formation and storage of new memories and we create the space needed by enabling forgetting of what is no longer required.

There is no one-size-fits-all magic amount of sleep. As individuals, we vary and our sleep patterns change at different ages, but for most adults, around 7-9 hours is a good average as determined by the world’s largest sleep study that published its findings in late 2018. This study also revealed how getting too little or too much shut-eye is bad for our cognitive abilities.

You know if you’ve had enough sleep if you can wake up at the desired time without the aid of an alarm clock feeling fresh and alert. If 3 presses on the “snooze” button, a cauldron of coffee and a kick from your partner is needed to get you out of bed, you may be a little sleep-deprived.

But you are not alone. The other finding from the sleep study confirmed nearly half of those surveyed were getting only 6.3 hours sleep at night. Splitting hairs?

No, that hour plus deficit quickly compounds into a chronic sleep debt that can’t be repaid with a weekend lie in.

Moreover, most of those who reported getting four hours or less performed their cognitive test as if they were 9 years older.

Sleep is a complicated process involving two biological systems, our circadian rhythm and the sleep – wake homeostasis mechanism along with a number of different genes, hormones and neurotransmitters.

Why do we sometimes wake up unrefreshed?

During sleep we go through a number of sleep cycles each lasting around 90 minutes that comprise a number of different stages.

As you fall asleep, which can take anything from a couple to 25 minutes you enter a light phase of sleep from which you can be readily woken from, and your heart and breathing rate start to slow down.

That’s why power naps are kept short and sweet. Trying to wake up from a deeper level of sleep leaves us feeling groggy and grotty – the so-called sleep inertia effect.

Deep sleep is the sleep needed for you to wake feeling refreshed and restored. It’s the sleep needed for memory consolidation to make it easier to retain and recall information, and for the production of growth hormone (super important for kids).

It’s also the time for the brain to restore energy after a busy day of thinking by boosting glucose metabolism and to induce greater calm through the stimulation of the parasympathetic system.

Sleep is the time for neuronal household maintenance and repair, and for flushing metabolic waste out of the brain in a unique process involving the glymphatic system which works best during deep sleep. It’s believed that poor sleep patterns disrupt this mechanism and increase the risk of neurodegenerative conditions.

The good news is if you are sleep deprived, your clever brain will move you to deep sleep more quickly.

How to boost deep sleep

Go to bed. Seriously. If you’re not in bed you’re not optimising your potential for enough deep sleep. Various sleep trackers can assist in giving you a clue as to how much time you’re spending in different stages of sleep. If you’re concerned by what the tracker is telling you – it’s time to seek help from your health practitioner or sleep specialist.

Have a bath or warm shower an hour before bed. The hot water warms of our peripheries leading to a more rapid drop of the body’s core temperature and helps us to fall asleep more quickly. Our body temperature is closely linked to the regulation of the sleep-wake cycle and is typically lower in the evening, drops to its lowest in the middle of the night before rising again as we prepare to wake up.

We talk about white noise and blue light, but did you know pink noise can be helpful for boosting deep sleep?

Pink noise is random noise like white noise but deeper and boosts deep sleep. It is currently being used in a small pilot study as a possible way to enhance memory and defer dementia in those with mild cognitive impairment.

Get some exercise in during the day. The huffy-puffy sort to get your heart rate up. Just don’t do it too close to bedtime as it may have the reverse effect and keep you awake!

Eating a low carbohydrate diet may also help, but more research is needed in this area to determine more about the what and the when.

How come some people get by with less sleep?

We’ve all met them. Those annoying people who constantly like to remind you they only get 4-5 hours sleep every night and they feel just fine.

While this apparent bravado all seems like a bit of one-upmanship, there is one of two scenarios playing out here.

1. They are completely deluded.

We cannot train ourselves to do with less sleep and get away with it in the longer term. Period. Sure, in the short term you can but, eventually, your physiology catches up with you and it can get pretty messy with burnout, mental ill health and other health-related problems. Just saying. Oh, and it puts you at greater risk of potential cognitive impairment and getting fat. Neither of which is particularly desirable nor is the prospect of creating false memories, making some pretty poor decisions and being unable to pay attention.

Overachievers, please take note!

The first insight to go when we are chronically tired is just how tired we really are. Which explains why we keep driving, when we should be pulling off the road to rest or stay up late or pull an all-nighter to complete some work or study for an exam.

2. They have a genetic variant.

Rats. Yes, there are the few, the 1% who do function normally on four hours of sleep at night and there are a number of famous people well known for their short sleeping habits. However, they are considered to have a sleep disorder!  It has been discovered that true short sleepers have a mutation in the gene hDEC-2. Much remains poorly understood about sleep and one of the questions being asked is, do true short sleepers get the restoration their brain needs during the day? We’ll have to wait a while to discover the answer.

Meanwhile, if you believe you are a “natural” short sleeper, according to Dr Buysse from the University of Pittsburgh Medical Centre only 5% of those who think they are, are correct. Flying by the seat of your pants on a wing and a prayer and too little sleep, might not be the ideal solution in our over-working, exhausted society.

What is the role of REM sleep?

Like deep sleep, REM has an important role in memory helping us to retain the information most relevant to us and embedding what we have learnt. The 90-110 minutes spent in dreamland is when we are busy pruning away unneeded memories while maintaining new synapses to strengthen memory over time.

One of the most common questions I get asked about sleep other than – “how can I get a better night’s sleep?”, “is why do I have such weird and wacky dreams and what do they mean?”

We spend about 2 hours of our time asleep dreaming each night but remember only a fraction of them.

As to how we should interpret our dreams, I’ll leave that to the experts.

With up to one-third of the world’s population in developing countries chronically sleep-deprived, the time is now to be more sleep aware.

Knowing why sleep matters is the first step towards placing a higher value on the need for sleep and creating better sleep habits.

Are you sleep aware?

Dr Jenny Brockis

Dr Jenny Brockis is a medical practitioner and internationally board-certified lifestyle medicine physician, workplace health and wellbeing consultant, podcaster, keynote speaker and best-selling author. Her new book 'Thriving Mind: How to Cultivate a Good Life' (Wiley) is available online and at all good bookstores.

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