Healthy brain, immune function depend upon sleep

Every wonder why you feel tired when you get sick? That is because your immune system is regulated by signaling compounds that are closely linked to sleep regulation. Feeling sleepy can actually be an early sign that you may be getting sick.

These compounds are called cytokines. They are excreted by certain cells in our body in order to turn on and off functions such as immunity, inflammation, and down or up-regulating genes. Similarly, hormones also are used for communication, but by comparison cytokines fluctuate more and originate from a wider range of cells.

If you don’t get enough quality sleep you are more likely to get sick after getting exposed to a virus, such as the common cold or flu. Much of our healing and recovery happens while we sleep when some cytokines are at higher levels and tell our body to rest.

You could divide sleep into four or five stages. When we start nodding off and twitching, like I do every time I go to a classical music concert, we are transitioning from awake towards asleep. Consciousness starts to decrease but the brain is still processing information and sound. We can be easily jolted into alertness if we hear something like our name.

Once we get further along into light sleep it is harder to be awakened. We spend about 3 percent of our time transitioning into this stage and about 50 percent actually in light sleep. This is when our body temperature starts dropping, muscles relax, and even kidney functions slow down. That’s how we can generally make it through the night without having to get up to go to the bathroom.

The next stage, deep sleep, happens about 20 percent of the time and is when our immune system is being strengthened. Specific disease fighting hormones, proteins, and chemicals are released during this time. The body then restores immune function that was used during the day for rapid isolation and destruction of invading pathogens.

Deep sleep is when we are the most relaxed, both our heartbeat and breathing are at their slowest. It is difficult to be awakened from this stage even from loud noises and our level of brain waves are the slowest. The thinking part of our brain is off-line while our body is repairing and rebuilding itself.

REM sleep, the final stage, is almost the opposite. In this period the body is off-line instead, even paralyzed, and our brains are extremely active. Breathing and heart rate are higher. This is when most dreaming happens, your eyes move around rapidly, and the mind clears itself of undesired memories and thoughts.

In addition to supporting our immune function, sleep is imperative to the health of your brain. During the day normal metabolic processing of oxygen creates free radicals that cause oxidative stress. The resulting damage can be repaired at night. Even new neurons can be made while we sleep. Also, a molecule which provides energy to cells called adenosine triphosphate can be replenished. Known as ATP, this is the fuel our brains will need when we wake up.

Cells in the brain will shrink while sleeping. This allows fluid in the glymphatic system to wash in and remove toxins accumulated during the day. One lab study showed a protein linked to Alzheimer’s, called beta-amyloid, moving out of the brain twice as fast during sleep than awake.

Most of our body can repair and reorganize throughout the day, but our brain and immune system also rely upon the night. These may be too focused on other tasks during the day, like thinking and fighting disease, and need to be shut down regularly for maintenance.

Stop on by if you want to chat more about sleep.

Scott Porter, a functional medicine pharmacist, is the director of the Center for Functional Nutrition at Sandpoint Super Drug.