Sleep-Cycle

Top 6 Health Benefits of a Good Sleep

Listed below are the top health benefits associated with a good Sleep!

Introduction

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Sleep has been defined as a state that allows for the effective processing (consolidation) of acquired information in the memory (R).

It is a state that increases efficiency by regulating its timing and reducing use when activity is not beneficial (R).

It can be divided into two, Rapid Eye Movement (REM) sleep and Non-Rapid Eye Movement (NREM) sleep. REM sleep occurs in cycles of 90 minutes while NREM sleep can be divided into four further stages (R).

Sleep Regulation

  • Sleep is regulated by 2 parallel mechanisms
  • Sleep pressure & circadian regulation (controlled by hypothalamus and suprachiasmatic nucleus (SCN))
  • Sleep pressure builds up during wakefulness and this continues until the person goes to sleep.  Adenosine (and other) accumulation is thought to play a critical role in this.
  • The circadian rhythm is a 24-hour biological cycle in the body. Wakefulness/fatigue is caused by projections from the SCN to the brain stem.
  • The SCN, which is involved in the circadian rhythm, can enhance wakefulness and opposes the fatigue that builds (homeostatic rhythm) up during the day.
  • The buildup of adenosine (and other factors) may also cause a cyclical shift in wakefulness and fatigue via a complex pathway in the hypothalamus that acts like a switch and shuts off the arousal system.
  • The circadian rhythm and homeostatic rhythm both produce a see-saw like effect of sleep and wakefulness.

The Health Benefits of Sleep

1) Sleep Improves Memory

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Sleep supports memory consolidation.

A study was conducted where some participants were allowed to sleep after learning a list of syllables while others stayed awake.

Results found that participants who slept could recall more than those who had stayed awake during the retention interval following learning (R).

Children had a greater declarative knowledge, that is, stored more factual information after a night of sleep versus a day of wakefulness, when compared to adults (R).

2) Sleep Improves Motor Skills

When tested in the morning after a period of rest (12 hours), adults showed 18.9-20.5% improvement in motor speed in a finger tapping task (for a motor skill). An equivalent period of time during wake after the task showed no significant benefit (R).

Other studies also observed successful sleep-related improvements in sequential finger skills when sleep followed initial learning within 24 hours (R).

3) Sleep Helps Regulate Appetite

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The hormones leptin and ghrelin are involved in appetite regulation and energy expenditure in humans.

Leptin is an appetite suppressing hormone which is responsible for increasing energy expenditure while ghrelin is produced in response to fasting and promotes hunger (R1,R2).

During sleep, levels of leptin and ghrelin rise. The rise in leptin cancels the effect of ghrelin on hunger (R).

Lack of sleep lowered leptin levels by 19%  and increased ghrelin by 28% when compared to levels during longer periods of sleep. The end result was a 24% increase in hunger and a 23% increase in appetite (R).

4) Sleep Helps Regulate Immune Response

Sleep is essential for immune function and can be altered during infection. 

Animal studies showed the sicker the animal the more disrupted the sleep. Even though all animals received the same infective dose, those that survived had higher sleep scores than those that died (R).

In a Human study, inflammatory cytokines such as TNF-α mediated altered sleep-wake behaviour, involved in the physiological sleep regulation and in the hypnotic effects of sedatives (R).

In placebo-controlled trials, endotoxins disrupt sleep (R).

5) Sleep Improves Health and Longevity

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Obtaining a good night’s sleep can help reduce the risk of cardiovascular diseases. The risk of a fatal heart attack was found to increase by 45% in adults who slept less than 5 hours or less per night (R).

Other studies showed that women in rehabilitation for heart attacks who were poor sleepers had a higher risk of recurrence (R).

Long-term studies were conducted on individuals with varying sleep habits. Large deviations of 3-4 hours from the standard 8 hours in healthy individuals yielded an increased mortality (R).

6) Sleep May Help Reduce Weight

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Laboratory and epidemiological evidence show that the increased risk of obesity is possibly linked to the effects of sleep loss on hormones that control appetite like leptin and ghrelin (R).

In one study participants with short sleep had reduced leptin and elevated ghrelin, this difference is likely to increase the appetite, possibly explaining the increased BMI observed with short sleep duration (R).

Amount of Sleep Needed for Good Health

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Consequences of Sleep Deprivation

Lack of sleep has varying effects on the body, from increased BMI to greater risk of cardiovascular diseases to reduced immune system functions.

While other factors can also affect health a long, restful night’s sleep is recommended for maintenance of good health (R).

Sleep Debt Will Cause:

  • Immunodeficiency and dysregulation – will cause and autoimmunity
  • Inflammation and oxidative stress
  • Obesity
  • Cognitive dysfunction
  • Imbalanced hormones
  • Heart attack risk increased by 45% in adults who slept less than 5 hours

Technical

During sleep memories temporarily stored in short term storage are moved to long-term storage (R).

Apart from memory stabilization, sleep-dependent memory processing  can also enhance and integrate memories into existing ones (R).

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