The Basics of Sleep

We sleep 30% of our lifetime and it is so common that nobody thinks about it.

The basic adult human need is seven to eight hours of good sleep. There is no shortcut –body biochemistry needs the full amount, and undisturbed sleep is required for optimal recovery and next-day performance. This need is completely universal and there are no regional or ethnic differences although babies may require up to 18 hours, and children and teenagers may also need more than adults.

Although the ideal sleep is often described as falling asleep quickly, followed by a long period of deep sleep period and a quick, refreshing wake-up period, the reality is somewhat different. Even during undisturbed sleep most people wake up a few times per night, related to the approximately five sleep cycles of around 90 minutes each.

Both deep sleep (most prominent in the first half of the night) and dream sleep (most prominent in the second half) are important for embedding information and recovering, and have an enormous effect on learning performance / capability.

However, modern society has extended our ‘active’ time and changed our natural day-night rhythm. There is also pressure to fit in more during a 24-hour period: learn, socialize, exercise, gain new experiences, see the latest television series and so on. These activities often come at the cost of sleep.

Sleep Patterns

We still do not fully understand why we sleep although there are several theories, none of which yet offers conclusive evidence. We do know the process of sleeping follows a very distinctive pattern including four stages comprising the ‘sleep architecture’:

Non-Rapid Eye Movement (NREM) Sleep

• Stage 1:  light sleep – this is when a person is half asleep and half awake
• Stage 2: true sleep – this normally occurs within about ten minutes of light sleep and is the most common stage of sleep over the night. Breathing and heart rate are regular and body temperature drops
• Stage 3/4:  deep sleep – this is an important restorative stage of sleep. It is also difficult to wake some one from this sleep stage.  Blood pressure drops, breathing becomes slower and muscles relax

Rapid Eye Movement (REM) Sleep
This is the stage of sleep during which the most vivid and complex dreaming occurs. Also breathing can be quite irregular. REM sleep is also an important restorative stage of sleep

We sleep in a repeating 90-110 minute cycles of NREM followed by REM sleep. NREM accounts for three quarters of all sleep and REM the remaining 25%.

The Circadian Rhythm
The Circadian Rhythm is the internal time-keeping clock for the body. It has an important influence on sleep and wakening and is regulated by the daily dark-light cycle. A regular schedule (wake up time and bed time) are important to establish a strong Circadian Rhythm, which is important to a good night’s sleep; jet lag and shift work can disrupt this.

Melatonin
Melatonin is an important hormone in the brain that influences the sleep-wake cycle and helps set the Circadian Rhythm to the surrounding environment. A rise in melatonin tells the body when it is time to sleep.

Why don't people get enough sleep?

Apart from various recognized sleep disorders, there are many reasons why people do not get enough sleep. These fall into two general categories, not being able to sleep (insomnia) and not allowing enough time to sleep (lifestyle choices).One frequent problem is that the environment is not conducive to sleep – the bedroom may be too hot, too noisy or too cold, the bed may be uncomfortable or too small or a sleeping partner may cause disturbance. A person’s lifestyle or mental state can also affect their quantity and quality of sleep. Common lifestyle challenges including irregular work patterns can knock the Circadian Rhythm off balance. Sleep can be affected by eating too much or going to bed hungry, smoking too much or drinking too much alcohol or caffeine. Sleep can also be impacted if a person is anxious, depressed, or dwelling on the day’s events or problems. Alternatively, a person may be experiencing hormonal changes, such as the menopause, which can lead to sleep problems in some individuals.

Sleep and Work

Sleep effects how a person looks, feels and performs in their daily life – so inevitably it also impacts performance and behavior at work. A good night’s sleep enables people to function during the day and studies show a direct link between the amount of sleep and general ability the following day. Not only does sleep loss impair the ability to concentrate, meaning decreased productivity throughout the day, it also has an impact on temperament, leading to mood swings.. Sleeplessness can lead to nodding off during the day and difficulty in concentrating on work.

Sleep Disorders

Obstructive Sleep Apnea (OSA)
OSA is a disorder characterized by airway collapse (behind the tongue) during sleep, which obstructs breathing. This can cause snoring, labored breathing, gasping and choking. This airway collapse followed by attempts to breathe, can lead to a fitful and restless night’s sleep. Sleep apnea can also cause headaches, a shortened attention span, memory loss, poor judgment, and lethargy or sleepiness. If untreated, it can contribute to the development of high blood pressure, diabetes, heart attacks, and strokes.

Insomnia
Insomnia occurs when a person cannot get enough sleep despite spending adequate time in bed. Symptoms include not being able to go to sleep, waking up for long periods throughout the night, waking up too early and not feeling refreshed after a night’s sleep. The general prevalence of chronic insomnia in the UK population is between 10 and 15%. There is no easy solution although behavioral changes and, on occasion, sleeping pills can make things considerably better.

Narcolepsy
This is a disorder characterized by extreme sleepiness during the day and, in some individuals, loss of muscle tone with anger or laughter. In most cases it is due to the absence of a particular chemical in the brain.

Delayed Sleep Phase Syndrome (DSPS)
DSPS is an abnormality of the circadian clock that causes the afflicted individual to sleep best if they go to bed very late and get up quite late the next morning. It affects up to 16% of young people and can be transient or persistent. People who suffer from this, but have to conform to conventional hours, will often have difficulty sleeping and thus suffer the consequences of sleep loss.

Advanced Sleep Phase Syndrome (ASPS)
ASPS is also an abnormality of the circadian clock and causes the individual to sleep best if they go to bed very early in the evening and get up very early.  During this time people sleep well. It is most common in the elderly.

Restless Leg Syndrome
This is a disorder characterized by discomfort in the legs, particularly in the evening,  that is primarily relieved by movement. It can be worsened by stress and can last for hours, thereby disturbing sleep.

Parasomnia
These are abnormal events during the night such as sleep walking or sleep talking, physically acting out dreams, or having the signs of extreme fear (sleep terrors). Each has a different cause and generally occur in a particular stage of sleep