You might feel the most immediate effects of poor sleep in the general demise of your ability to function effectively throughout the day. You might find it hard to concentrate, feel cranky, over-emotional or stressed.
Of course, one night of short sleep won't put you at serious risk, but lack of adequate sleep over time can be extremely detrimental to both your physical and mental health. Poor sleep has even been associated with a shortened lifespan.
The role of sleep
Sleep is not an “option”, it is something our bodies need to do. Why we need to sleep still remains unclear, but we know there are physical, mental and emotional components.
Sleep helps your brain work properly. While you sleep, your brain is hard at work forming the pathways necessary for learning and creating memories. When we get sufficient sleep we are able to maintain normal levels of cognitive skills. This includes things such as speech and memory as well as our ability to think.
Sleep functions also help to repair cell damage and restore energy lost during awakening. Major restorative functions, including tissue repair, muscle growth and growth hormone release, also occur while we sleep.
In addition sleep plays an important role in our physical health and is involved in healing and repair of your heart and blood vessels.
The sleep cycle
There are five stages of sleep and each distinct stage serves a different purpose.
This is the lightest stage of sleep, the transition phase, where you feel yourself drifting off. You don't spend too much time in Stage 1 sleep, typically five to ten minutes, just enough to allow your body to slow down and your muscles to relax.
The second stage of sleep is still considered light sleep. Your brain activity starts to slow down, as well as your heart rate and breathing. You’re beginning to reach a state of total relaxation in preparation for the deeper sleep to come.
Stage 3 and Stage 4
These are deep sleep stages, with stage 4 being more intense than stage 3. It's harder to rouse you during this stage, and if someone woke you up, you would feel disoriented for a few minutes.
It is during the deep stages of sleep that the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system.
This is the stage of sleep when you dream. It is also referred to as "active sleep" or REM sleep. During this stage blood flow, breathing, and brain activity increases. You can have intense dreams during this stage of sleep as the brain is very active.
You cycle through all five stages several times (on average four to six times) each night, not always in the same order. A complete sleep cycle takes an average of 90 to 110 minutes.
The majority of healthy adults require between 7.5 to 8.5 hours per night, around 5 sleep cycles. However the modern 24/7 society leads to disturbances of our natural sleep cycle.