By Sarah Bennett from Sarah Bennett Nutrition


The elixir of life.

Know that old saying, “I’ll sleep when I’m dead”?
Well, you’ll be dead sooner if you don’t get your sleep!

The less sleep you have the more likely you are going to suffer from ill-health and even die earlier!

How much does sleep actually affect us?

There’s still so much we don’t know about sleep but there’s one thing we do know;

Sleep is extremely important; it plays a huge role in metabolic homeostasis, is critical to both cognitive and physiological function and has an integral role in learning and memory.

A lack of sleep is detrimental to your health, but also can make it harder for you to reach your body composition and fitness goals.

Sleep regulates our appetite, helping control body weight and is linked to the fitness of our cardiovascular system, lowering blood pressure while keeping our hearts in good condition.

If you’re getting 6 hours of sleep or less, your time to physical exhaustion drops by up to 30% and the ability of your lungs to expire CO2 and inhale oxygen decreases, which is why it always feels so much harder to exercise after a bad nights sleep.

A lack of sleep also means a higher injury risk. One study showed a 60% increase in probability of injury comparing people who get 9 hours of sleep a night, to those who get 5.

How does a lack of sleep affect hunger?

There are two hormones that control appetite: ghrelin and leptin.

Ghrelin regulates hunger and leptin regulates appetite (satiety or fullness).

Poor sleep decreases the ‘satiety hormone’ leptin and increases the ‘hunger hormone’ ghrelin.

So, even if you are eating enough food to ward off hunger, your body continues signalling for you to eat because the ‘I’m full’ signal isn’t working.

Not only do sleep-deprived people crave more food, the types of food they crave tend to be the high-calorie sort.

Studies have also found, when you are dieting and not getting sufficient sleep, 70% of all the weight you lose will come from lean muscle, not fat. Our body becomes resistant at giving up fat when it’s under slept.

Lack of sleep is a critical factor of the obesity epidemic


After 20 hours of being awake, you are as physically and cognitively impaired as you would be if you were legally drunk. Drowsy driving kills more people on the roads than alcohol or drugs combined.

Wakefulness, compared to sleep, is low level brain damage.

During deep sleep at night, there is a sewage system in the brain that cleanses the brain of all the metabolic toxins that have accumulated throughout the day.

Scientific evidence linking sleep disruption and cancer is now so damning that the World Health Organization has officially classified night time shift work as a “probable carcinogen.”

We can’t use naps to regain sleep we’ve lost. Sleep is not like a bank. We can’t accumulate a debt and hope to pay it off on the weekend.

Matthew Walker, a sleep neuroscientist and author of the book ‘Why We Sleep’, estimates that if you pull an all-nighter, and then are allowed to sleep as long as you want the next night, you’ll sleep longer but you’ll only get back 3-4 hours of that lost total 8.

Napping however, can be beneficial for those with sleeping disorders or shift workers and can also help daytime sleepiness in some people.
(The main issue for most people is the grogginess you feel when you wake up from a nap).

Even for individuals who generally get the sleep they need on a nightly basis, napping may lead to benefits in terms of mood, alertness, and cognitive performance.

Practically, if naps do not interrupt your normal sleep patterns, they can be beneficial; however, if you can’t sleep because you had a nap then it’s probably not a good idea.

Memory and cognition are negatively affected with sleep deprivation.

Humans need more than seven hours of sleep each night to maintain cognitive performance.

After ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours.

The interesting thing is that people don’t realise the increasing cognitive losses, which means the human mind cannot accurately sense how sleep-deprived it is when sleep-deprived.


1) Set a consistent sleep schedule (including weekends)
Consistent bedtime/wake up time establishes a normal circadian rhythm
Set a night-time sleep and wake time schedule (yes including weekends- you don’t have to get up).

2) Room temperature
A colder room temperature allows us to sleep deeper and darkness allows for optimal release of melatonin and optimal sleep cycle distribution.
Studies have shown the ideal room temperature for sleep is around 18deg Celsius.
Interestingly, you can still fall asleep if the temperature is lower than this but warmer than this, and it is much harder to fall asleep.
Having a warm bath before bed can help because of the drop in temperature when you get out.

3) Take naps.
As a species, our ‘natural’ sleep pattern is biphasic: sleeping during two periods over 24 hours.
This means that, if possible, you should take a short 15-30-minute nap during the day alongside your 7-9 hours sleep during the night.

Remember though, napping doesn’t make up for inadequate night time sleep. However, a short nap can help to improve mood, alertness and performance.
Don’t take naps too late into the afternoon or close to when you actually go to sleep as this can affect your ability to fall asleep at night.

Limit naps to 30 minutes.

4) Limit blue light
Blue light and bright light at night basically confuses your brain and delays the natural circadian rhythm.
The blue light on screens can interfere with our melatonin production. Either don’t use your phone/computer 1 hour before bed or switch to night mode.

5) Read a book
Instead of browsing Facebook or Instagram before bed, read a book.
Practice some meditation on an App like Headspace or breethe. Even if it’s just 5 mins of breathing. It can help calm your mind and “turn off” which means you relax and fall asleep quicker.

6) Avoid drinking too much fluid in the evenings.
You’ll be forced to wake up during the night to go to the toilet which will inevitably mess with your sleep, especially if you have to turn on the lights–this will mess with melatonin secretion.

7) Stimulants
Stimulants like caffeine late in the day can disrupt the normal sleep cycle and inhibit certain sleep hormones which can lead to worse quality of sleep. Not to mention they make it harder to fall asleep. (“Caffeine has an average half-life of five to seven hours.)
Alcohol may seem to help you fall asleep, but it actually prevents you from getting REAL sleep. Alcohol often leads to broken sleep and seriously interrupts the deep REM sleep we need. Also, it puts you into a tranquilized state which is not ideal.

8) Eating before bed
You want to go to bed reasonably satiated. Meaning, you’re not stuffed and uncomfortable, neither starving, as this can interfere with sleep.

Steer clear of heavy or rich foods, fatty or fried meals, spicy dishes, citrus fruits, and carbonated drinks which can trigger indigestion for some people and can lead to painful heartburn that disrupts sleep.

9) Ensure adequate exposure to natural light.
This is particularly important for people who may not go outside frequently. Exposure to sunlight during the day, as well as darkness at night, helps to maintain a healthy sleep-wake cycle.

10) Sleep aids
Using an eye mask and earplugs can help you get higher quality sleep, especially if the person next to you is prone to waking you up!

Magnesium supplements may help with sleep but only if you have low levels. Some people find 5HTP can help as well.

Avoid sleeping tablets long term (or at all) as they can interfere with your natural sleep pattern (and can negatively affect you the day after).

If you struggle with insomnia, CBT-I (cognitive behavioural therapy for insomnia) has been shown to be much more effective than sleeping pills.

You NEED 7-9 hours of sleep per night.

Sleep is the single most effective thing we can do to reset our brain and body health each day.

“There does not seem to be one major organ within the body, or process within the brain, that isn’t optimally enhanced by sleep…The physical and mental impairments caused by one night of bad sleep dwarf those caused by an equivalent absence of food or exercise.”
– Matthew Walker, Why We Sleep.

(Ref: Matthew Walker Why We Sleep)