What Is Sleep?

          

           Sleep is a health practice and  all of are us engage in it. Some of the definitions of sleep are as following;

“A natural periodic state of rest for the mind and body, in which the eyes usually close and consciousness is completely or partially lost, so that there is a decrease in bodily movement and responsiveness to external stimuli”.

“A periodic state of physiological rest during which consciousness is suspended and metabolic rate is decreased.”

  There are two broad categories of sleep;

1- Rapid eye movement (REM);

         

         During REM sleep, eyes dart back and forth, breathing and heart rate flutter, most muscles are paralyzed and during this time we often experience vivid (clear) dreaming.

           

             This stage of sleep is marked by beta waves, and it is believed most important for turning knowledge into long term memories, and also for solving many problems from the previous day.

 An adult usually reaches REM approximately every 90 minutes. During this stage of sleep oxygen consumption by brain is higher as compared to awake state.

2- Non-rapid eye movement (NREM or non-REM);

            

 NREM sleep consist of four stages;

Stage 1; the lightest and the earlier stage of sleep, This is a stage between sleep and wakefulness. The muscles are active, and the eyes roll slowly, opening and closing moderately. This stage is marked by theta waves.

Stage 2; In this stage, it gradually becomes harder to awaken the sleeper. In this stage body temperature drops, breathing and heart rate also even out. During this stage brain waves alternate between short bursts called sleep spindles and large K-complex waves.

Stage 3, 4; The sleeper is less responsive to the environment and during this stage many environmental stimuli no longer produce any reactions.

            All these four stages are important for strengthening immune system, restoring energy, and also are responsible for promoting body to release more growth hormones.

Timing and duration of sleep;

 Sleep timing is controlled by the circadian clock (inner timekeeping), temperature-fluctuations, and our behaviors also control the timing of sleep.

Researches indicated that need of sleep is different in different age groups;

               

                Age                                                    Sleep Needs

      Infants (0–11 months)                                    14 to 15 hours  

      Preschoolers (3–5 years)                               11 to 13 hours

      School-age children (5–10 years)                  10 to 11 hours

     Adolescents (10–17 years)                            8 to 9 hours

      Adults, including elderly                                 7 to 9 hours

Sleep and health;

        

        Thirty-nine percent of adults sleep less than 7 hours on weeknights, and 54% of people over age 55 report insomnia at least once in a week.

        

            It is also observed that insufficient sleep affect thinking process, mood and work performance. Any of us who has spent a sleepless night knows well that how un-pleasant the following can be.

Some sleep disorders;

  Some major sleep disorders are following;

1-Circadian rhythm sleep disorders

2-Fatal familial insomnia

3-Narcolepsy

4-Restless leg syndrome (RLS)

5-Insomnia

6-Sleep apnea

Causes of Sleep Deprivation;

          

  Major causes are;

1-Depression or some stressful events in life cause sleep related problems.

2-Abuse of alcohol is also main cause of sleep deprivation.

3-Some genetic problems in gene determining quality of sleep is also major cause.

4-Disturbance in the surroundings, as noise.

5-Disruption  of circadian rhythm.

6-Excessive intake of caffeine

 6-Side effects of certain medications

Sleep Deprivation Effects;

1-Slowed physical responses and reflexes, driving in this condition can be dangerous

2-Sleep deprivation has many adverse effects such as;

3- Problems related to immune functioning

4-It can also reduce pain tolerance

5-Can impair metabolic functioning

6-Severity of hypertension can increase due to it

7-It can also increases risk of developing coronary heart diseases

8-Another problem caused by sleep deprivation is weight gain

Treatment;

           

 Treatment of disturbed sleep;

1-A number of behavioral interventions can reduce this problem, including relaxing therapy, control of sleep related behaviors.

2-Drinking a glass of warm milk will be effective.

3-Avoid excessive consumption of caffeine or alcohol.

4-A slight change in life style may lead to a good sleep.

5-In severe cases some medicines to aid sleep can also be used but only by the prescription of doctors.

           Most important thing is to maintain your sleep timings. you should strictly follow the timings you have set for sleep it will help you to avid problems related to sleep.

Sleep in non-human animals;

In animals it is difficult to observe neurological sleep state, In these cases, sleep may be defined using behavioral characteristics such as minimal movement, postures typical for the species, and reduced responsiveness to external stimulation.

Herbivores spend a long time to gather and consume their food, so they sleep less each day as compared to carnivores of the same size which can consume adequate supply of meat in a single sitting.

Horses and other herbivorous ungulates can sleep while standing, but must necessarily lie down for REM sleep (which causes muscular) for short periods. For example, Giraffes, only need to lie down for REM sleep for a few minutes at a time.

 Birds and mammals have cycles of non-REM and REM sleep (as described above for humans), though birds' cycles are much shorter and they do not lose muscle tone to the extent that most mammals do, this is the reason that birds do not fall down while sleeping.

Some aquatic mammals and some birds can sleep with one half of the brain while the other half is awake.