National Sleep Awareness week is this week! Sleep is so often underrated. It really is true what they say..."Sleep better. Feel better." So you might wonder why sleep actually makes us feel so much better. Why do we really need so much of it? What exactly is happening when we sleep? Let's start with the basics.
At first glance, it may seem obvious what sleep is. We know that we lie down at night and close our eyes when we go to sleep. According to the Oxford English Dictionary, sleep is a "condition of body and mind which typically recurs for several hours every night, in which the nervous system is inactive, the eyes closed, the postural muscles relaxed, and consciousness practically suspended." Until the 1950's, 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.
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. There are chemicals that keep our brain active while we are awake such as serotonin and nor epinephrine. Then there is a chemical called adenosine that builds up in our blood while we are awake and causes drowsiness. Neurons at the base of our brain begin signaling when we fall asleep and therefore "switch off" the signals that keep us awake. The chemical adenosine also begins to break down while we are sleeping.
During sleep, we usually pass through five stages of sleep: 1, 2, 3, 4, and REM (rapid eye movement) sleep. The stages progress in a cycle and then start over again at stage 1. We spend about 50% of our total sleep time in stage 2, 20% in REM, and the remaining 30% in the other stages. Infants, however, spend most of their time in REM sleep.
Stage 1- This stage is light sleep. We can be awakened very easily in this stage. Our eyes move very slowly and our muscle activity slows. Many even experience sudden muscle contractions.
Stage 2- Our movements stop and our brain waves become slower with occasional bursts of rapid waves.
Stage 3 & 4- These two stages are considered deep sleep. It's more difficult to wake someone in these stages. There is no eye movement or muscle activity.
REM- When we switch to REM sleep, our breathing becomes more rapid, irregular, and shallow, our eyes jerk rapidly in various directions, and our limb muscles become temporary paralyzed. Our heart rate and blood pressure increase, and this is where dreams occur. The first REM occurs about 70-90 minutes after we fall asleep and as the night progresses and we go through the cycle of stages, our REM stage increases in length while deep sleep decreases.
The amount of sleep each person needs depends on many factors, including age. For most adults, 7-8 hours appears to be the best amount, but if sleep deprived the amount should be increased. Your body demands sleep and will demand more if starved. Our judgment, reaction time, concentration, memory, and other functions will be impaired if sleep deprived. Our immune system is detrimentally affected without sleep and could therefore open doors for diseases to occur. Hallucinations and mood swings can also occur if sleep deprived. If you fall asleep within 5 minutes of lying down, then you are probably sleep deprived.
Scientists are still trying to learn exactly why people need sleep and so much of it. We truly need sleep to live and survive. Sleep appears to be necessary for our nervous systems to work properly. It is thought that those neurons used while we are awake actually need to be “switched off” and “shut down” in order to repair themselves for a new active state. They can become depleted in energy and polluted with byproducts of normal cellular activities that they begin to malfunction. Sleep also gives the brain a chance to exercise important neuronal connections that might otherwise deteriorate from lack of activity. Deep sleep actually coincides with the release of growth hormone in children and young adults. Many of the body’s cells also show increased production and reduced breakdown of protein during sleep and this is important because proteins are the building blocks needed for cell growth and repair. Turning off the active parts in the brain that control emotion and decision making processes may even help people maintain optimal emotional and social functioning while they are awake.
While there is so much involved while we sleep and how it can affect our bodies, there is still a lot we do not know and a lot that cannot be easily covered. Sleep research is ongoing and is a key component in scientists truly understanding the brain. It’s important to listen to your body and sleep when it is telling you it is deprived. Better yet, maintain a set routine of good quality sleep to help your body feel its best. Sleep can help keep you healthy, prevent many diseases, and make you look and feel better too.