The Art of Sleep

Every night, without any effort on your part, your body performs one of the most extraordinary acts of healing in nature. Cells repair, hormones rebalance, memories are filed away and the brain washes itself clean. Sleep isn't time switched off. It's medicine, and it's free.

The night shift inside you

Sleep comes in cycles of around 90 minutes, each moving through lighter sleep, deep sleep and dreaming sleep. Each stage has its own work to do:

• Deep sleep (slow-wave sleep), mostly in the first half of the night, is the body's repair time. It's when most growth hormone is released, muscles and tissues are rebuilt, and the immune system is strengthened.
• REM sleep, the dreaming stage, comes more in the second half of the night. It helps us process emotions, consolidate learning and spark creative connections.

Cutting sleep short, or waking often, robs us of the stages we need most.

The brain's cleaning cycle

In 2013, scientists discovered something remarkable. During sleep, the spaces between brain cells widen by around 60%, allowing fluid to wash through and flush away waste, including proteins linked with Alzheimer's disease.¹ This clean-up system, called the glymphatic system, works mainly while we sleep.

It may help explain a striking finding: in a study that followed nearly 8,000 UK adults for 25 years, people who regularly slept six hours or less in their 50s and 60s had around a 30% higher risk of developing dementia later.²

What poor sleep does to the body

• Immunity. When volunteers were given cold viruses, those who usually slept less than six hours were over four times more likely to catch a cold than those who slept more than seven.³
• Blood sugar. After less than a week of four-hour nights, healthy young men handled sugar so poorly that their results resembled those of people at risk of diabetes.⁴
• Appetite and weight. Just two nights of short sleep lowered leptin, the hormone that tells us we're full, by 18%, and raised ghrelin, the hunger hormone, by 28%. Appetite, especially for sweet and starchy foods, rose with it.⁵
• Stress. Poor sleep raises evening cortisol, which in turn makes it harder to sleep. (See The Cortisol Clock.)
• Mood. Sleep loss makes the brain's alarm centre more reactive, and long-term sleep problems are closely linked with anxiety and depression. (See Where Body Care Meets Mind.)
• Lifespan. A review of studies covering more than a million people found that regularly sleeping too little, usually less than six or seven hours a night, was linked with a 12% higher risk of early death.⁶

Sleep is the one medicine everyone can take, and the one so many of us leave on the shelf.

Melatonin: the hormone of darkness

As daylight fades, a tiny gland deep in the brain, the pineal gland, begins to release melatonin. Often called the hormone of darkness, it tells every cell in the body that night has come. Melatonin levels rise through the evening, peak in the early hours and fall by morning, the mirror image of cortisol. (See Living by the Sun.)

But melatonin is far more than a sleep signal. Scientists now see it as one of the body's most remarkable protective molecules:

• A powerful antioxidant. Melatonin neutralises damaging free radicals directly, and its breakdown products are antioxidants too, creating a cascade of protection.⁷
• A guardian of mitochondria. It gathers in the mitochondria, the cell's power stations, helping protect them from wear and tear.
• An immune ally. Melatonin helps regulate the immune system and calm inflammation.
• A gut hormone too. Remarkably, the gut contains far more melatonin than the brain, where it helps protect the stomach lining and regulate digestion.
• A friend to the brain. In one trial, melatonin was as effective as a standard preventive medicine at reducing migraine attacks, with fewer side effects.⁸
• A traveller's aid. A Cochrane review found melatonin effective at easing jet lag.⁹

Melatonin, light at night and cancer

Our ancestors spent their nights in darkness. Today, many of us live under artificial light until bedtime, and some work through the night. Light at night suppresses melatonin, and researchers believe this may matter for our long-term health.

The World Health Organization's cancer agency classes night-shift work as "probably carcinogenic to humans", partly because of its disruption of the body clock and melatonin.¹⁰ In the long-running Nurses' Health Study, women who had worked rotating night shifts for 30 years or more had a 36% higher risk of breast cancer.¹¹ In the laboratory, melatonin has been shown to slow the growth of some cancer cells, and researchers are studying it alongside conventional cancer treatment. These are early findings, but they add weight to an old idea: we need real darkness at night.

Melatonin and longevity

Melatonin production falls steeply as we age. By later life, many people make only a fraction of the melatonin they made in their youth,¹² which may help explain why sleep often becomes lighter and more broken with age. Because melatonin protects cells, mitochondria and the immune system, scientists are exploring whether supporting it could help us age more healthily. In animal studies the results have been encouraging, and it's an active area of longevity research. (See A Natural Age.)

Raising your own melatonin naturally

• Get bright light in the morning. Daylight early in the day sets your body clock, so melatonin rises on time in the evening.
• Dim the lights in the evening. Even ordinary room lighting before bed suppressed melatonin and shortened its release by about 90 minutes in one study.¹³ Use lamps instead of overhead lights, and warm-coloured bulbs.
• Put screens away an hour before bed, or use night mode.
• Sleep in real darkness. Blackout curtains or an eye mask help.
• Try tart cherries. Montmorency cherries are a natural source of melatonin, and tart cherry juice increased melatonin levels and improved sleep in a small trial.¹⁴ Walnuts, pistachios, oats and tomatoes also contain small amounts.

Sleeping more deeply

• Keep regular hours. Going to bed and waking at the same time every day is one of the most powerful things you can do.
• Keep it cool. The body needs to cool down to fall asleep. A bedroom of around 16–18°C suits most people.
• Take a warm bath or shower one to two hours before bed. As your body cools afterwards, sleep comes more easily.¹⁵ For a deeper wind-down, try a 20-minute soak in 500g of Epsom salts.
• Mind your caffeine and alcohol. Caffeine can linger for hours, and alcohol may help you drop off but disrupts deep and dreaming sleep later in the night.
• Eat earlier. Finish your last meal two to three hours before bed.
• Calm the mind. Meditation, breathing practices or a few minutes of journalling can quieten a racing mind. (See The Sound of Stillness and The Healing Breath.)
• Nap wisely. If you nap, keep it under 20–30 minutes and before mid-afternoon.

Nutrients and herbs for sleep

• Magnesium helps the nervous system relax, and is found in leafy greens, nuts, seeds and beans.
• Chamomile, a gentle, calming herb, makes a soothing evening tea.
• Lemon balm and passionflower are traditionally used to quieten a busy mind.
• Valerian has been used for centuries to support sleep, though it suits some people far better than others.
• Lavender, as an aroma or a specially prepared oil, can help ease the anxiety that keeps us awake.

As always, the right herb depends on the person and their energetics. A herb that settles an overheated, racing mind may not suit someone cold and depleted. To learn more, read The Architecture of Balance. For accuracy and safety, it's best to seek guidance from a qualified practitioner rather than self-prescribing, especially if you take any medicines.

At Rootwise, sleep is often one of the first things we look at, because when sleep improves, almost everything else follows. We'll look at your rhythms, stress, diet and constitution, and build a plan to help you rediscover deep, restoring rest.