According to the National Institute of Neurological Disorders and Stroke, sleep is an important part of a person’s daily routine and is essential for many things including health, learning, and mood. Considering that the average person spends approximately a third of their lives sleeping, it stands to reason that sleep is as essential to living as eating and drinking.

While the process of sleeping is complex and science does not yet fully understand it, research has shown that it is essential in creating new memories and removing toxins in one’s brain. In addition, sleep affects almost every tissue in the body including the heart, lungs. Chronic sleep deprivation, or poor sleep quality, has been shown to increase the risk of cardiovascular disease, high blood pressure, diabetes, depression, and obesity.
The Sleeping Brain

The hypothalamus, a small structure deep in the brain, acts as control center for the sleep/wake cycle. Within the hypothalamus is the suprachiasmatic nucleus (SCN) which receives information about light from the eyes and controls sleep rhythm. People that have damage to this area of the brain have trouble with the sleep cycle. Most blind people have some sense of light and dark and are able to adjust to normal sleep/wake cycle.

The brainstem is located at the base of the brain and communicates with hypothalamus to control transition between wake and sleep. Brainstem and hypothalamus produce chemical called GABA which reduces arousal centers in both areas of the brain. The brainstem is also very involved in the rapid eye movement (REM) stage of sleep and sends signals to relax muscles so we don’t act out our dreams.

The thalamus relays information from the senses to the cerebral cortex, the part of the brain that process information from short to long-term memory. During most stages, the thalamus is quiet but during REM sleep it actively sends messages to the cortex that help create dreams.

The pineal gland is a small gland located within the brain. It receives signals from SCN and increases production of melatonin, a hormone that helps you sleep.

The basal forebrain is located near the front, bottom part of the brain. It helps promote sleep and wakefulness and releases adenosine which supports sleep. Caffeine counteracts sleepiness by blocking adenosine.

The mid-brain acts as an arousal system.

The amygdala is the part of the brain that processes emotions and is active during REM sleep.
What happens when we sleep?

There are two basic types of sleep: REM and non-REM. Your body cycles through all of the stages of REM and non-REM sleep during the night, with REM periods increasing toward the early morning hours. All sleep stages are extremely important. Some stages help you to become rested and heal, while others help you to remember and learn. People will go through several sleep cycles per night, though the length of each stage can vary.

Stage 1- Non-REM. This is a very short stage of light sleep, usually lasting several minutes. Your heart rate, breathing, eye movements, and brain waves slow.

Stage 2- Non-REM. This is still a light phase of sleep. Your heartbeat and breathing are still slowing. Your muscles are relaxing and your temperature drops. Eye movements are now stopped. Brain wave activity is slowed but there are bursts of electrical activity.

Stage 3- Non-REM. This is the deep sleep stage gives you a rested feeling. Your heartbeat and breathing are slowed to their lowest levels. Your muscles are relaxed, and you are difficult to wake. Brain waves are very slow. The blood supply is increased to the muscles. Body tissue grows and is repaired, and hormones are released.

REM sleep. Occurs approximately 90 minutes after falling asleep. Your eyes move rapidly from side-to-side. Breathing is fast and irregular. Heart rate and blood pressure increase to near waking levels. Brain wave activity is mixed and similar to waking levels. This is the stage where most of your dreaming occurs and is the most vivd. Your limbs are temporarily paralyzed. As you age, you will spend less of your sleep in the REM stage. Memory consolidation occurs and mood balance is affected by this stage.
How much sleep is necessary?

Although everyone is a bit different regarding their personal sleep requirements, there are significant differences in the sleep needs of people throughout their lifespan. For example, babies need as much as 16-18 hours of sleep for growth, particularly for brain development. Children and teens need as much as 9.5 hours of sleep. Most adults need approximately 7-9 hours per night, although this decreases significantly after age 60. Seniors need less sleep and it tends to be shorter and lighter, with multiple awake periods, nightly. In addition, most people tend not to get enough sleep due to hectic schedules, stress, and the use of technology at night.
Tips for a restful sleep.
• Get on a regular schedule.
• Exercise 20-30 minutes daily but not near bedtime.
• Avoid caffeine late in the day.
• Relax before bed by taking a bath or reading.
• Create a restful environment that is void of bright lights, loud noises, and is at a comfortable temperature.
• Avoid TV or other screens in your bedroom.
• Avoid lying awake in bed. If you can’t sleep, try doing something else until you feel sleepy such as reading.