Is There Science Behind a Good Night's Sleep?

In a word, absolutely. In fact, there is a considerable amount of science behind a good night's sleep, and if you're a person who doesn't get adequate sleep, you may be suffering in ways that you don't even realize. There are quite a few stressors that contribute to disrupt a person's quality of sleep at night, so it's essential that you try to develop good lifestyle habits, including a healthy diet, to promote a good night's sleep.

People who get insufficient sleep over an extended period of time often develop physical health issues such as high blood pressure, heart disease, and obesity. Research is now showing that consistently inadequate sleep can also lead directly to a greater likelihood of developing Alzheimer's disease.

The science behind a good night's sleep

Everyone has an internal body clock that operates on a 24-hour system known as circadian rhythms, and this controls when you feel tired and when you feel more refreshed. The urge to sleep will increase throughout the day, in correspondence with the increasing level of adenosine, and once you do get to sleep, the body begins breaking down the accumulation of this sleep-causing adenosine. Science has also determined that light has a big influence on your circadian rhythms.

Your brain contains a whole separate center of nerve cells that help figure out whether it's day or night, by processing available natural light. When the level of natural light begins to diminish during the later part of the day, your body starts to release more melatonin, a sleep-inducing hormone. When the sun comes up in the morning and natural light increases, the body stops producing melatonin and instead releases cortisol, which causes you to feel more refreshed and alert.

The four stages of sleep

There are four primary stages of sleep that most people go through in the course of a night's sleep, those being Stage 1 NREM, Stage 2 NREM, Stage 3 NREM, and REM sleep. Here is what science has determined happens during each of these stages:

• Stage 1 NREM - this phase only lasts a few minutes, and is characterized by a slowing down of your heart rate, breathing, and eye movements.

• Stage 2 NREM - the longest of the four sleep stages, this phase is marked by eye movements ceasing, relaxation of muscles, and lower heart rate. It is a deeper sleep phase than the first stage.

• Stage 3 NREM - during this phase, your heart rate, breathing, and muscles are as relaxed as they will get during the evening, and that contributes strongly toward the feeling of alertness you have the next day.

• REM - the first REM phase normally kicks in about 90 minutes after you fall asleep. Your heart rate and breathing will increase, and your arms and legs become paralyzed, probably to prevent you from acting out on the dreams that occur during this phase. As people age, they spend less time in a REM state, and more time in the three NREM phases.

These four stages of sleep will go through cycles every night, until you wake up the next day. NREM sleep normally comprises about 80% of your total sleeping time, and that percentage usually increases as people age. It is necessary for most people to obtain about 7 - 9 hours of sleep every night, although young people typically require even more, to support growth and development.