Sleep (

Sleep is a state of reduced mental and physical activity in which consciousness is altered and sensory activity is inhibited to a certain extent. During sleep, there is a decrease in muscle activity, and interactions with the surrounding environment. While sleep differs from wakefulness in terms of the ability to react to stimuli, it still involves active brain patterns, making it more reactive than a coma or disorders of consciousness.

Sleep occurs in repeating periods, during which the body alternates between two distinct modes: REM and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body. Dreams are a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep.

During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; these are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems. The internal circadian clock promotes sleep daily at night. The diverse purposes and mechanisms of sleep are the subject of substantial ongoing research. Sleep is a highly conserved behavior across animal evolution, likely going back hundreds of millions of years.

Humans may suffer from various sleep disorders, including dyssomnias such as insomnia, hypersomnia, narcolepsy, and sleep apnea; parasomnias such as sleepwalking and rapid eye movement sleep behavior disorder; bruxism; and circadian rhythm sleep disorders. The use of artificial light has substantially altered humanity's sleep patterns. Common sources of artificial light include outdoor lighting and the screens of electronic devices such as smartphones and televisions, which emit large amounts of blue light, a form of light typically associated with daytime. This disrupts the release of the hormone melatonin needed to regulate the sleep-cycle.

Source: Sleep (

What REM sleep does for your brain—and 3 ways to trigger more of it | Patrick McNamara

This interview is an episode from @The-Well, our publication about ideas that inspire a life well-lived, created with the @JohnTempletonFoundation. Subscribe to The Well on YouTube ► Watch Patrick McNamara’s next interview ► Neurosc

A daytime nap is good for the brain

Regularly finding time for a little snooze is good for our brain and helps keep it bigger for longer, say University College London researchers. The team showed nappers' brains were 15 cubic centimetres (0.9 cubic inches) larger - equivalent to delaying ageing by between three and six years.

Fatty tongues could be main driver of sleep apnoea

image copyrightSCIENCE PHOTO LIBRARYA sleep disorder that can leave people gasping for breath at night could be linked to the amount of fat on their tongues, a study suggests.

Will we ever...hibernate in space?

The year is 2039, and you're an astronaut on your way to Mars. You're only three months into the eight-month-long journey, and already your body is facing an onslaught of radiation from outer space. In zero gravity, your bones and muscles are at risk of wasting away.

How the seasons change our sleep

The arrival of spring often heralds a welcome change after the long, hard winter months. The Sun stays up for longer, the days grow warmer, the first flowers begin to bloom, and in many countries the clocks tick forward into daylight savings time to lengthen our evenings.

The tech helping people get a better night's sleep

Have you ever laid in bed at night, with sleep tantalisingly out of reach while thoughts ricocheted around your head? If so, then the plight of Lisa Holland from Chesterfield in Derbyshire, may strike a chord.

Sex and no sleep may be killing endangered quolls

Endangered male northern quolls are giving up sleep for more sex - and it could be killing them, according to new research from Australia. The study found that males travel long distances in search of mating partners, often giving up sleep in the process.

The forgotten medieval habit of 'two sleeps'

It was around 23:00 on 13 April 1699, in a small village in the north of England. Nine-year-old Jane Rowth blinked her eyes open and squinted out into the moody evening shadows. She and her mother had just awoken from a short sleep.

From Knowable Magazine

On dry nights, the San hunter-gatherers of Namibia often sleep under the stars. They have no electric lights or new Netflix releases keeping them awake.

What really happens when babies are left to cry it out?

In 2015, Wendy Hall, a paediatric sleep researcher based in Canada, studied 235 families of six- to eight-month-old babies. The purpose: to see if sleep training worked.

Can 'sleep leadership' help banish burnout?

Fried, co-founder and CEO of US software company Basecamp, says prioritising sleep – and ensuring he’s regularly getting enough hours of quality rest – is a major part of what makes him a good leader.

Regular 10pm bedtime linked to lower heart risk

There appears to be an optimal bedtime - between 10pm and 11pm - linked to better heart health, say researchers who have studied 88,000 volunteers.

Why teenage sleep is so important for mental health

It's late morning and the teenagers in the house are still fast asleep long after you've got up. Should you rush upstairs and pull them out of bed by their feet? It may be tempting, but the answer is probably no.

The psychology behind 'revenge bedtime procrastination'

Emma Rao spent almost three years on China’s notorious ‘996 schedule’: working from nine in the morning to nine in the evening, six days a week. Rao, who is originally from Nanjing, moved to financial hub Shanghai about five years ago to work for a multinational pharmaceutical company.

sleep insomnia