SleepSmith.com Home
HOME CONTACT US 

Conventional Size Mattresses For Sale...Sleep Smith® How Will My Mattress or Mattress Set Be Shipped Twin Size Mattresses For Sale Full Size Mattresses For Sale Queen Size Mattresses For Sale King Size Mattresses For Sale
Special Size Mattresses For Sale...Sleep SmithSpecial Size Mattresses For Sale...Sleep Smith® Twin XL Mattresses For Sale Antique Size Mattresses For Sale 3/4 Mattesses For Sale Full XL Mattresses For Sale California Queen Mattresses For Sale California King Mattresses For Sale Sleep Smith Sleeper Sofa Mattresses For Sale Sleep Smith Waterbed Replacement Mattresses
Tall Man Mattresses For Sale...Sleep Smith 7 Foot Long Twin Size Tall Man Mattresses For Sale Full Size Tall Man Mattresses For Sale Queen Size Tall Man Mattresses For Sale King Size Tall Man Mattresses For Sale
Split Box Springs For Sale...Sleep Smith® Full Size Split Box Springs For Sale Queen Size Split Box Springs For Sale
Metal Bed Frames For Sale...Sleep Smith® Standard Metal Bed Frames For Sale Heavy Duty Metal Bed Frames For Sale California Size Metal Bed Frames For Sale Hook On Rail Sets For Sale Hybrid Bed Frames For Sale Low Profile Bed Frames For Sale Bolt On Bed Frames For Sale Rail Systems For Sale
Deep Pocket Bed Sheets For Sale...Sleep Smith® Luxury and Basic Deep Pocket Sheet Sets For Sale
Special Size Sheet Sets For Sale...Sleep Smith® Luxury and Basic Sheets Antique Sheet Sets For Sale Luxury and Basic Three Quarter Sheet Sets For Sale Premuim and Basic Waterbed Sheet Sets For Sale
Platform Beds For Sale Platform Beds Various Styles and Sizes For Sale
Heated Mattress Pads Heated Mattress Pads
Bedroom Furniture For Sale Bedroom Furniture For Sale
Better Sleep Articles Bed Bugs And Dust Mites Bedframes for Mattresses General Mattress Information Good Sleep Tips Medical Sleep Disorders Poetry To Sleep By Psycho Analysis Sleep Psychoma - SOUL SLEEP Sleep Advice From The Past Sleep Drugs And Supplements Sleepy Fairy Tales The Importance of Restful Sleep The Mystery Of Sleep Understanding Sleep Legal Issues And Sleep The Consumer Product Safety Commission New Federal Mattress Flammability Standard
 
spacerUnderstanding Sleep >>Better Sleep Articles >> Understanding Sleep
Articles in Understanding Sleep
  1. Dreaming and REM Sleep
  2. How Much Sleep Do We Need?
  3. Keeping Time to Circadian Rhythms
  4. Sleep and Circadian Rhythms
  5. Sleep and Disease
  6. Sleep Deprivation
  7. Sleep: A Dynamic Activity
  8. Sleepless Society
  9. The Stages of Sleep
  10. What Does Sleep Do For Us?

Sleep: A Dynamic Activity

Sleep: A Dynamic Activity

Until the 1950s, most people thought of sleep as a passive, dormant part of our daily lives. We now know that our brains are very active during sleep. Moreover, sleep affects our daily functioning and our physical and mental health in many ways that we are just beginning to understand.

Nerve-signaling chemicals called neurotransmitters control whether we are asleep or awake by acting on different groups of nerve cells, or neurons, in the brain. Neurons in the brainstem, which connects the brain with the spinal cord, produce neurotransmitters such as serotonin and norepinephrine that keep some parts of the brain active while we are awake. Other neurons at the base of the brain begin signaling when we fall asleep. These neurons appear to "switch off" the signals that keep us awake. Research also suggests that a chemical called adenosine builds up in our blood while we are awake and causes drowsiness. This chemical gradually breaks down while we sleep.

During sleep, we usually pass through five phases of sleep: stages 1, 2, 3, 4, and REM (rapid eye movement) sleep. These stages progress in a cycle from stage 1 to REM sleep, then the cycle starts over again with stage 1 (see figure 1 ). We spend almost 50 percent of our total sleep time in stage 2 sleep, about 20 percent in REM sleep, and the remaining 30 percent in the other stages. Infants, by contrast, spend about half of their sleep time in REM sleep.

During stage 1, which is light sleep, we drift in and out of sleep and can be awakened easily. Our eyes move very slowly and muscle activity slows. People awakened from stage 1 sleep often remember fragmented visual images. Many also experience sudden muscle contractions called hypnic myoclonia, often preceded by a sensation of starting to fall. These sudden movements are similar to the "jump" we make when startled. When we enter stage 2 sleep, our eye movements stop and our brain waves (fluctuations of electrical activity that can be measured by electrodes) become slower, with occasional bursts of rapid waves called sleep spindles. In stage 3, extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves. By stage 4, the brain produces delta waves almost exclusively. It is very difficult to wake someone during stages 3 and 4, which together are called deep sleep. There is no eye movement or muscle activity. People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after they wake up. Some children experience bedwetting, night terrors, or sleepwalking during deep sleep.

When we switch into REM sleep, our breathing becomes more rapid, irregular, and shallow, our eyes jerk rapidly in various directions, and our limb muscles become temporarily paralyzed. Our heart rate increases, our blood pressure rises, and males develop penile erections. When people awaken during REM sleep, they often describe bizarre and illogical tales – dreams.

The first REM sleep period usually occurs about 70 to 90 minutes after we fall asleep. A complete sleep cycle takes 90 to 110 minutes on average. The first sleep cycles each night contain relatively short REM periods and long periods of deep sleep. As the night progresses, REM sleep periods increase in length while deep sleep decreases. By morning, people spend nearly all their sleep time in stages 1, 2, and REM.

People awakened after sleeping more than a few minutes are usually unable to recall the last few minutes before they fell asleep. This sleep-related form of amnesia is the reason people often forget telephone calls or conversations they've had in the middle of the night. It also explains why we often do not remember our alarms ringing in the morning if we go right back to sleep after turning them off.

Since sleep and wakefulness are influenced by different neurotransmitter signals in the brain, foods and medicines that change the balance of these signals affect whether we feel alert or drowsy and how well we sleep. Caffeinated drinks such as coffee and drugs such as diet pills and decongestants stimulate some parts of the brain and can cause insomnia, or an inability to sleep. Many antidepressants suppress REM sleep. Heavy smokers often sleep very lightly and have reduced amounts of REM sleep. They also tend to wake up after 3 or 4 hours of sleep due to nicotine withdrawal. Many people who suffer from insomnia try to solve the problem with alcohol – the so-called night cap. While alcohol does help people fall into light sleep, it also robs them of REM and the deeper, more restorative stages of sleep. Instead, it keeps them in the lighter stages of sleep, from which they can be awakened easily.

People lose some of the ability to regulate their body temperature during REM, so abnormally hot or cold temperatures in the environment can disrupt this stage of sleep. If our REM sleep is disrupted one night, our bodies don't follow the normal sleep cycle progression the next time we doze off. Instead, we often slip directly into REM sleep and go through extended periods of REM until we "catch up" on this stage of sleep.

People who are under anesthesia or in a coma are often said to be asleep. However, people in these conditions cannot be awakened and do not produce the complex, active brain wave patterns seen in normal sleep. Instead, their brain waves are very slow and weak, sometimes all but undetectable.

 
Check out FineWebStores.com
AccentFurniture.com
AlphabetRug.com
BeanBagChairs.com
BigManRecliners.com
BraidedRugSale.com
ButcherBlockKitchen.com
CaliforniaKingBedFrames
DaybedCovers.com
DecorativeBookends.com
GrandfatherClockSale.com
KingSizeBedFrame.com
LumbarSupportRecliner.com
OldWestSigns.net
OuFurniture.com
OutDoorThermometer.com
PlatformStorageBed.com
QueenSizeBedFrames.com
TerrariumSale.com
WardianCase.com
WaterbedAuthority.com
WeatherVaneSale.com
WhatBedBugsLookLike.com

HOME TEXTILES
12VoltMattressWarmers.com
100%EgyptianCottonSheets
AdjustableBedSheetSets
AntiqueSizeSheets
CaliKingSizeSheets
CaliQueenSizeSheets
CollegeDormRoomBedding
CotSheetSets.com
DeepPocketBedSheets.com
DustRufflesForDaybeds.com
ElectricMattressWarmer.com
ExtraDeepPocketBedSheets
HospitalBedSheetSets.com
OlympicQueenSheetSets
RollAwayBedSheets.com
SleeperSofaSheets.com
SplitQueenSheets.com
ThreeQuarterSheets.com
TruckSleeperSheets.com
TwinXLSheetsets.com
WaterbedSheetSale.com
XLFullSheets.com

CITY SKYLINES
AtlantaSkylinePicture.com
BaltimoreSkylines.com
BostonSkylines.com
CharlotteSkyline.com
CitySkylinePictures.com
DallasSkylines.com
DenverSkylines.com
DetroitSkyline.com
FortWorthSkylines.com
FramedPanoramas.com
HoustonSkylines.com
IndianapolisSkyline.com
LASkylines.com
LasVegasPicture.com
LasVegasSkyline.com
LondonSkylines.com
LosAngelesSkylines.com
LouisvilleSkylines.com
MiamiSkylinePicture.com
MilwaukeeSkyline.com
MinneapolisSkylines.com
NashvilleSkylinePicture.com
NewOrleansSkyline.com
NewYorkCityPanorama.com
NewYorkCitySkylinePicture
New-York-Skyline.com
NewYorkSkylineAtNight.com
ParisSkylines.com
PhiladelphiaSkylines.com
PhillySkylines.com
PittsburghSkylines.com
SanAntonioSkylines.com
SanDiegoSkyline.com
SanFranciscoSkyline
SeattleSkylines.com
SkylineOfNewYork.com
TokyoSkylines.com
TorontoSkyline.com
VancouverSkylinePicture
WashingtonDCSkylines

MATTRESSES
AbeFeller.com
Adjustablebeds.com
AntiqueSizeMattressSet.com
CaliforniaQueenMattress.com
DoubleSizeMattress.com
FullSizedMattress.com
KingSizedMattressSet.com
QueenSizeMattress.com
SplitBoxSprings.com
SplitQueenBoxSprings.com
TallMattress.com
ThreeQuarterMattressSet
TwinMattress.com
TwinXLMattressSet.com