Sleep disorders are not just annoying, they can also affect your productivity. Insomnia and sleep apnea are two of the most common sleep disorders, affecting about 40 million Americans, and more than 20 million experience intermittent problems during the night. The number of people affected by sleep problems is on the rise, and these conditions negatively affect our ability to function at work, drive, and participate in social activities. These disorders cost the U.S. economy an estimated $16 billion a year in medical costs, and the cost of indirect consequences are likely to be higher. Many doctors have defined more than 70 sleep disorders, and most are treatable with proper diagnosis and treatment. Some of the more common ones include insomnia, sleep apnea, and restless legs syndrome.

Sleep improves memory and improves emotional health. Research has also linked deep sleep to feeling rested the next day. During deep sleep, blood pressure, heart rate, and breathing slow down. Brain activity continues to slow down. Until recently, scientists did not understand the reasons why we need sleep, but the research has shown that each stage of sleep is associated with specific changes in the body and supports the overall health of various systems. In fact, the most basic physiological changes in each stage of sleep are listed below.

REM and non-REM stages are also known as “wake” and “dream” sleep. These stages occur during the daytime, while non-REM sleep occurs during the night. The latter sleep stage helps us tune out the external world and process memories. Researchers are still trying to determine exactly what happens during REM sleep, but there are a few common patterns that all people share. And they are all crucial for our health. If you have a hard time sleeping, you should consider the research on sleep and REM.

Stage 1 involves light sleep and the transition to deeper sleep. Your heart rate and breathing slow down, and muscles relax. You may also feel your body temperature and eye movements decreasing. The duration of this stage of sleep is longer than those of the other stages. Stage 2 is often the most restful sleep of the night. This stage also plays an important role in making you feel refreshed and rejuvenated. You will be in this stage for about two-thirds of the night.

Adults need between seven and nine hours of sleep per night, but their sleep patterns change with age. Babies sleep 16-18 hours daily to stimulate their brain development. School-age children and teens need about 9.5 hours of sleep each night. After age 60, most adults need between seven to nine hours of sleep. After sixty, nighttime sleep tends to be lighter and shorter. People who suffer from chronic lack of sleep tend to take medications that interfere with sleep.

Your body’s internal clock regulates your sleep and wakefulness. Your body’s internal body clock, or circadian rhythm, produces a chemical called adenosine that supports your sleep drive. Caffeine blocks adenosine, which counteracts sleepiness. The amygdala, an almond-shaped structure located in the brain, is involved in emotion processing and is activated during REM sleep.