The first part of the cycle is non-REM (Rapid Eye Movement) sleep, which is composed of four stages. The first stage comes between being awake and falling asleep. The second is light sleep, when heart rate and breathing regulate and body temperature drops. The third and fourth stages are deep sleep. Though REM sleep was previously believed to be the most important sleep phase for learning and memory, newer data suggests that non-REM sleep is more important for these tasks, as well as being the more restful and restorative phase of sleep.
As you cycle into REM sleep, the eyes move rapidly behind closed lids, and brain waves are similar to those during wakefulness. Breath rate increases and the body becomes temporarily paralysed as we dream.
The cycle then repeats itself, but with each cycle you spend less time in the deeper stages three and four of sleep and more time in REM sleep. On a typical night, you’ll cycle through four or five times.
Sleep loss and sleep disorders affect an individual’s performance, safety, and quality of life. Almost 20 percent of all serious car crash injuries in the general population are associated with driver sleepiness, independent of alcohol effects. Further, sleep loss and sleep disorders have a significant economic impact. The high estimated costs to society of leaving the most prevalent sleep disorders untreated are far more than the costs that would be incurred by delivering adequate treatment. Hundreds of billions of dollars a year are spent on direct medical costs associated with doctor visits, hospital services, prescriptions, and over-the-counter drugs. Compared to healthy individuals, individuals suffering from sleep loss, sleep disorders, or both are less productive, have an increased health care utilization, and an increased likelihood of accidents.
The public health consequences of sleep loss, night work, and sleep disorders are far from benign. Some of the most devastating human and environmental health disasters have been partially attributed to sleep loss and night shift work-related performance failures, including the tragedy at the Bhopal, India, chemical plant; the nuclear reactor meltdowns at Three Mile Island and Chernobyl;
Sleep loss and sleep disorders affect an individual’s performance, safety, and quality of life. Almost 20 percent of all serious car crash injuries in the general population are associated with driver sleepiness, independent of alcohol effects. Further, sleep loss and sleep disorders have a significant economic impact. The high estimated costs to society of leaving the most prevalent sleep disorders untreated are far more than the costs that would be incurred by delivering adequate treatment. Hundreds of billions of dollars a year are spent on direct medical costs associated with doctor visits, hospital services, prescriptions, and over-the-counter drugs. Compared to healthy individuals, individuals suffering from sleep loss, sleep disorders, or both are less productive, have an increased health care utilization, and an increased likelihood of accidents.
The public health consequences of sleep loss, night work, and sleep disorders are far from benign. Some of the most devastating human and environmental health disasters have been partially attributed to sleep loss and night shift work-related performance failures, including the tragedy at the Bhopal, India, chemical plant; the nuclear reactor meltdowns at Three Mile Island and Chernobyl; as well as the grounding of the Star Princess cruise ship and the Exxon Valdez oil tanker. Each of these incidents not only cost millions of dollars to clean up, but also had a significant impact on the environment and the health of local communities.
as well as the grounding of the Star Princess cruise ship and the Exxon Valdez oil tanker. Each of these incidents not only cost millions of dollars to clean up, but also had a significant impact on the environment and the health of local communities.Yet the moment you rest your head on your pillow and switch out the lights, all external distraction and engagement with the outside world is gone. Your mind is entirely free to turn in on itself, either to fret about all that’s happened or to worry about the next day to come – the past and the future being the two main sources of anxious thoughts.
Psychologists are increasingly realising that one of the least effective ways to deal with intrusive, troubling thoughts is to try to fight them – doing so only increases their salience, making them hang around for longer. Instead, it’s better to acknowledge and accept the thoughts, then let them pass.
For anxious thoughts about the day that you’ve just had, one practical way to do this is by writing an emotionally expressive daily journal before bed. A pair of researchers at the University of Oxford found that people with insomnia who spent time before bed writing openly about their worries and concerns subsequently took less time to fall asleep. It’s as if the writing exercise got the anxious thoughts out of their heads and onto paper, making it easier to drift off.
As it was now pitch dark within their tiny aerie[1] they lay down upon their blankets to try to gain, through sleep, a brief respite of forgetfulness.
Clayton lay facing the opening at the front, a rifle and a brace of revolvers at his hand.
Scarcely had they closed their eyes than the terrifying cry of a panther rang out from the jungle behind them. Closer and closer it came until they could hear the great beast directly beneath them. For an hour or more they heard it sniffing and clawing at the trees which supported their platform, but at last it roamed away across the beach, where Clayton could see it clearly in the brilliant moonlight—a great, handsome beast, the largest he had ever seen.
During the long hours of darkness they caught but fitful snatches of sleep, for the night noises of a great jungle teeming with myriad animal life kept their overwrought nerves on edge, so that a hundred times they were startled to wakefulness by piercing screams, or the stealthy moving of great bodies beneath them.
[1] Aerie – a secure cabin to sleep