Why we all need sleep

August 06 2016

Science is discovering that we've catastrophically underestimated the importance of sleep.

Dr David Hillman cringes when he hears people boasting that they get by on five hours sleep a night or less. As one of the world’s leading experts on sleep, he doesn’t think that’s cool. Dr Hillman likens health to a three legged stool, and many people sit on a three-legged stool. After exercise and diet, sleep is the third leg of that stool. But many people, he says, are happy to balance on a two-legged stool, with sleep considered optional, or even a sign of laziness.

Because the brain appears to function on not enough sleep, people assume it’s OK to miss an hour here or a few hours there. “The problem with the human brain is that it can carry around a sleep debt and you can still function. But in reality, you aren’t functioning optimally, especially in terms of things like reaction times, thought processing and even your mood,” Dr Hillman says.

But not getting enough sleep has far greater consequences than just lowering your level of alertness through the day. In fact, just as we’re now discovering that too much sugar is really bad for you, we’re also finding that too little sleep can be just as bad.

Why do we sleep?

Incredibly, despite the fact that we spend 36 percent of our lives asleep, it’s only over the last year that neuroscience has begun to understand what sleep is for.

We’ve always correctly guessed that sleep involved some kind of restoration and repair, but what we didn’t know is how low-level the processes are. Sleep actually switches on hundreds of genes involved in restoration of the body and repair of metabolic pathways. Not getting enough can actually alter activity in genes that control metabolism, inflammation, immunity and stress.

This was conclusively shown by a ground-breaking study recently in which a group of volunteers at Surrey University in the UK were forced to sleep less than six hours a night for a whole week. At the end, they had altered function in 711 genes that were critical for general health, and since then, science has figured out that prolonged lack of sleep can result in chronic low-level inflammation which can lead to a range of serious health conditions and cardio-metabolic diseases such as hypertension, stroke or irregular heartbeat.

But, according to sleep experts, there is also powerful evidence that sleep helps the brain process information and lay down memories. “What science thinks happens is that when you’re awake, certain neural circuits in your brain are constantly bombarded with information, “ says Dr Hillman. As the day wears on they start to lose their sensitivity.

“They go through a phenomenon called downregulation, meaning they lose their sensitivity as the bombarding gets harder. Eventually, the tiredness and the lethargy that you experience and the less efficient processing of the information by the brain, plus slower reaction times, are a manifestation of that. During sleep those circuits get rested and they upregulate; their sensitivity to these signals returns and they’re ready to receive a whole lot more information the next day.”

Another sleep expert, circadian neuroscientist Russell Foster from Oxford University in the UK, says “memory consolidation is very important. However, it’s not just the laying down of memory and recalling it. What’s turned out to be really exciting is that our ability to come up with novel solutions to complex problems is hugely enhanced by a night of sleep. In fact, it’s been estimated to give us a threefold advantage. Sleeping at night enhances our creativity. And what seems to be going on is that, in the brain, those neural and synaptic connections that are important are linked and strengthened, while those that are less important tend to fade away.”

A cascade of effects

While repair, restoration and the laying down of memories appear to be the main reasons we sleep, science has discovered sleep does so much more, such as:

Builds muscle with growth hormone: Although the brain releases several hormones during sleep, growth hormone is probably the most vital to those who exercise due to its importance in muscle building. Responsible for stimulating cell growth, reproduction and regeneration, growth hormone is also linked with increased metabolism.

Hormone homeostasis: The stress hormone cortisol is responsible for many processes in the body, and while sleeping can lower its levels, not getting enough sleep can raise them. Increased cortisol lowers levels of growth hormone, therefore slowing down healing and impairing normal cell regeneration, which is bad news if you’re injured.

Increases energy: Glucose and glycogen are our main sources of energy and are particularly important as a fuel source for endurance events beyond 90 minutes. Sleep deprivation may decrease glycogen synthesis and slow the storage of glycogen.

Reduces appetite and hunger: Missing out on sleep increases appetite and hunger by elevating the body’s concentrations of the appetite-stimulating hormone ghrelin and decreasing the levels of the satiety hormone leptin, making weight management harder work than it should be. Dr Hillman says “there’s strong links between sleep disruption and dietary intake. Shift workers are well known for picking at food and being overweight.”

Decrease in Basal Metabolic Rate (BMR): BMR is the amount of energy your body expends while performing basic bodily functions such as breathing and muscle repair, and the higher your BMR, the more calories you burn. Metabolism has been found to actually decrease in the early stages of sleep when the brain uses less glucose, but is reversed in the later stages of sleep. If you cut short your sleep, then you’re more likely to miss out on the benefits associated with a higher metabolism when your body switches to restoration mode.

And these are simply some direct impacts. We don’t have the space to go into the chronic long-term effects of lack of sleep, such as cardiovascular disease, diabetes and even cancer.

How much sleep do we need?

Sleep experts believe 7.5 to 8 hours a night is ideal – but they acknowledge this will vary with different individuals. As one put it, how much sleep would you get if you could sleep as much as you wanted, without work, children or other things getting in the way? Think back to your last holiday. How many hours did you sleep without interruptions waking you?

Are afternoon naps worthwhile or do they interfere with sleep?

Experts says afternoon naps may be necessary if overnight sleep is of inadequate length. However, if naps are too late and too long they can interfere with nighttime sleep. One problem with naps is the groggy, sleep inertia feeling you can have for a while after waking from them. Try to nap for no more than 20 minutes, since anything longer puts you into slow wave sleep which causes grogginess on waking.


TOP 5 Sleep Tips

1. Make enough time for sleep

As strange as it sounds, not allocating enough time for sleeping (because of busy lives) is the major reason you become sleep-deprived. At least 7.5 to 8 hours a night is recommended.

2. Keep sleep regular

Don’t keep changing your bed time. If you can’t control when you fall asleep, then always wake up at the same time. Try and wake with natural light, which suppresses melatonin. As part of that, don’t hit the snooze button.

3. Make the bedroom welcoming

Get the best mattress you can afford and turn the bedroom into a haven you feel relaxed in. Many bedrooms are exposed to noise, outside light or disruptive partners (or children).

4. Have a wind down routine

Indulge in things that relax rather than stimulate you, such as a hot bath or herbal drink (don’t surf the web or answer emails).

5. Get tech out of the bedroom

Computers and phones emit blue light that suppresses sleep hormone melatonin.

6. Don't obsess about not sleeping

Obsessing about not sleeping when you can’t get to sleep makes it worse. Think of other, more pleasant things.