Rabu, 04 Januari 2012

How Much Sleep Do We Need

When getting up in the morning, the large majority of us still feel incredibly tired and find it a challenge to get up. If you were to ask somebody about the amount of sleep they get and if they would want more, I'm sure a lot of people would say they get a reasonable amount or less, and would accept the invitation to have more sleep.

There are however others, who hate to sleep in late and don't want to miss out on any part of the day.

For me, I would rather get up early, as I consider the morning to be the best part of the day. If you would like to know some of the other reasons why I like to get up early, then I'll refer to an earlier post of mine: 10 Benefits of Being an Early Riser.

Stages of Sleep

Sleep is divided into two general types: REM (rapid eye movement) and NREM (non-rapid eye movement), each with there own unique features. Your sleep is made up of five stages: 1 - 2 - 3 - 4 - REM. When you fall into sleep, you begin at the first stage and work your way through, before coming out of the other side.

A sleep cycle can take anywhere from 90 to 120 minutes going through each of the stages of sleep. This is considered 1 cycle. After finishing, it just starts over again.
Before reading any more, if you find it hard to drop off to sleep, I've written a previous post named: How to Relax Before Bed.

Stage 1: The beginning stage is just a light sleep, with the recognisable drifting in and out. Sudden movements of muscles can be common, but you're eye and body movement do slow down overall, and you're in a position where you can be woken easily.

Stage 2: This stage is when brain waves (the measurement of activity of your brain) slow down, roughly fifty percent of your time spent sleeping is spent in stage 2. Occasionally sleep spindles take place (rapid brief bursts of brain activity). 

Stage 3: This is the first stage of deep-sleep, where delta waves and faster waves. Whilst in this stage, it can be difficult to wake a person, disorientation and grogginess are usual for someone is does awaken during this stage, and normally for several minutes. 

Stage 4: After stage 3, the second stage of deep sleep occurs, slow delta waves are almost exclusively being produced by the brain. Like stage 3, it is also very hard to wake up a person. The two stages of deep sleep are important for a refreshing feeling to take effect. Sleep will not feel very satisfying if these two stages are too short.

REM: About twenty percent of sleep for adults is spent in the REM stage. As you enter into REM sleep, your breathing becomes fast, irregular and shallow. Heart rate and blood pressure increase, as-well as quickened eye movement and less mobile muscles.

Beginning about 70-90 minutes into a cycle, REM is the stage in which dreams occur and is quite short in the first cycle, increasing in length towards the morning.

Despite quite a lot being known about sleep, researchers don not fully understand REM sleep or the reasons for the occurrence of dreams.

Amount of Sleep

The amount of sleep is dependant on age, infants and children needing more. A newborn spends about 9 hours of sleep in the REM stage, studies suggest that school children need 10-11 hours of sleep a day.

Newborn: up to 18 hours per day
12 Months: 14-18 hours per day
12-36 Months: 12-15 hours per day
36-62 Months: 11-13 hours per day
5-12 Years: 9-11 hours per day
Adolescent: 9-10 hours per day
Adults, including elderly: 7-8 hours per day.

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