Getting enough sleep is one of the biggest contributors to good health – it gives our bodies that crucial time they need to grow, heal and repair.
I was getting it all wrong for about five years – only getting three to four hours’ sleep a night, which is not good. On average, less than six hours a night or more than nine over a sustained period increases our risk of developing an illness – short sleep has been associated with obesity, type-2 diabetes and cancer, for example. I’m doing really well now, but I literally have to treat sleep like a job, not because I can’t sleep once I’m in bed, but because there seem to be a thousand reasons/noises/people/distractions that prevent me from just turning off and getting into bed. I’ve consciously got myself into a routine that I stick to five or six days a week, and frankly has underpinned all the things I’ve picked up and tried to express in this book. The following information is fascinating, geeky stuff that I’ve learnt from super-dude Professor Jason Ellis, one of only a few qualified sleep scientists in the UK.
THE PROCESSES OF SLEEP
We spend every day going through two processes. The first is called process S – it’s the drive we all have to go to sleep. It works a bit like being hungry then satiating that feeling by eating. From the moment we wake up, we start developing our drive to go to sleep again – it will increase all day, then drop once we sleep. The second is known as process C, which is our natural body clock – the circadian rhythm. It pretty much works on a 24-hour basis, but weirdly Jason tells me it’s actually around 24¼ hours for many of us. This explains why sleep is so fragile – our internal system is constantly fighting an external world, kind of like jetlag. We’re always a bit behind or a bit ahead, so regular bedtimes and getting into a good routine is really helpful.
REGULATING SLEEP PROCESSES
There are two hormones that are key to the success of our sleep. Melatonin, a natural hormone, helps us get to sleep. It builds up as it gets dark, reaching a peak at around 4am when it starts to decline. On the other hand is cortisol, the stress hormone. It’s got a bit of a bad rep but it allows us to walk, talk, exercise and do what we need to do during the day. It works in the opposite way – we start to produce cortisol in the early hours of the morning to get us ready to wake up. That’s the basics – anything that disrupts either of those processes or the intersection between them is a sleep disorder. So, with all that in mind, let’s go on to what happens when we’re actually asleep, and the repeating cycle we go through every night.
THE 90-MINUTE SLEEP CYCLE
This cycle repeats throughout the course of a night:
STAGE ONE – that warm cosy feeling when we get into bed. Our brainwaves start to slow – about five minutes
STAGE TWO – as we drift off, we get progressively deeper and might experience a jolt, like we’re falling off something. This is the ‘hypnagogic jerk’ and one explanation for it is that we no longer need cortisol, so our muscles tense and jerk to excrete excess quickly. We’re at the official onset of sleep – our brainwaves get slower still and more rhythmic, and the majority of our memory consolidation occurs, including black and white dreaming (45–55% of our night)
SLOW WAVE SLEEP – we go into a very deep sleep and it’s hard to wake ourselves (or others!) – our brainwaves have spaced out. This stage is the only sleep period where our immune systems work at 100% – we’re healing, producing anti-cancer cells, anti-allergens and cleaning the body – this is why we sleep a lot when we’re poorly. This is 13–23% of our night
STAGE TWO (AGAIN) – we pop back into stage two, although we don’t wake up, we’re conscious enough to check our environment is safe, then we move on to . . .
REM CYCLE – this sleep stage is really important for our memory and mind, and clears all the toxins in the brain. It only lasts about five minutes in its first iteration, but is 20–25% of our night. If we don’t sleep well, our memory is shot the next day and our problem-solving ability is reduced – good to know. We dream in colour now, and if we don’t remember our dreams it just means we’re consolidating our memory really well
TIPS FOR A GOOD NIGHT’S SLEEP
Most importantly of all, remember that the quality of your sleep is much more important than the quantity.
Avoid bathing in the two hours before going to bed, and don't exercise in that time either – both activities raise the body temperature, not giving it enough time to decrease before trying to sleep
Create a cool, dark and quiet environment – we instinctively use light and dark as cues. If it helps, wear ear plugs and an eye mask – I do!
Blue light – from electronics – is very unhelpful. If light is essential, go for deep yellow or red, which have long wavelengths and don’t interrupt sleep
Naps are a good thing, but should be kept to 20 minutes to prevent the body going into a longer sleep cycle, which would mean we wake up groggy, not refreshed, as we’ve interrupted that deeper cycle
Hydrate well throughout the day, and reduce liquid intake slightly from about 5pm onwards, to avoid bathroom trips in the night, disrupting sleep cycles
Try not to eat in the two hours before going to bed, or the body will be going through the digestive process as well as trying to get to sleep. Keep it simple!
Helpful foods to increase melatonin levels are kiwi fruit (eat two in the evening), cherries, walnuts, unripe bananas, raspberries, tomatoes and jasmine rice
Remove clocks from the bedroom – they can create tension and distraction if constantly checked, adding unnecessary pressure. Keep an alarm far enough away from the bed so it can’t be reached in the night
Everyday Super Food by Jamie Oliver is published by Penguin Random House ⓒ Jamie Oliver Enterprises Limited (2015 Everyday Super Food) Photographer: Jamie Oliver