Sleep science is still an evolving field, with plenty of mysteries yet to be uncovered. One thing we do know about sleep is its vital importance to good health. Sleep affects every system in the body, from digestion, the cardiovascular system and even immune health. Recent research has highlighted the importance of sleep for proper immune function.

Sleep Deprivation Health Risks

Without quality sleep, every aspect of our health suffers. The standard process of cellular regeneration is disrupted. Wounds and injuries heal more slowly, and there's less protection against the aging process. Toxins in the body aren't processed out, and the cardiovascular system is impacted. While one or two nights of poor sleep probably won't do much harm, long-term sleep deprivation can cause serious health problems.

One system, in particular, that's impacted by poor sleep is your immune system. Your body requires a certain amount of sleep to produce new cells, including the specialized cells that fight off infections. This is a two-way street: disruptions to the immune system can also cause disruptions to your sleeping patterns, causing a negative feedback loop.

Sleep and Immune System Health

The immune system is highly complex, involving various organs throughout the body. When pathogens attack, the immune system can mount a range of defenses against them. These include innate immunity -- immunity we're born with and which we retain throughout our lives. The other type of immunity is adaptive immunity. This is created when the immune system encounters a threat and learns to recognize it.

The immune system uses a variety of different cells to fight off infections. One of the most important type of immune cells is the leukocyte or white blood cell. Leukocytes identify and attack pathogens entering the body so that infections can't take hold. They produce various chemical messengers, including cytokines, which alert other cells to a pathogen's presence and trigger an immune response.

Immune reactions include responses such as inflammation. That's why so many autoimmune diseases have inflammatory symptoms, such as swollen joints. An optimally functioning immune system defends against invading pathogens while leaving the body's cells alone and not mounting a "defense" against allergens such as pollen or pet dander. When you're not sleeping properly, this balance can be disrupted. This can lead to a greater risk of both infections and autoimmune problems like allergies or arthritis.

The Sleep Hormone and Immune Health

Recent research has unearthed an even more direct connection between sleep and immune health. This direct link is through the hormone melatonin. Melatonin is a regulator of the circadian rhythm and its secretion is highest during the nighttime hours. Daylight and other sources of light (including blue light from cell phones and other devices) inhibit melatonin secretion and can disrupt the normal circadian rhythm. That’s why excessive viewing of blue-light emitting devices near bedtime (phones, tablets, etc.) can disrupt refreshing sleep.

But melatonin does more than just regulate the circadian rhythm. Scientists term it as a master regulator of immune health and inflammation as well. As sleep is a restorative process that is necessary for the body to repair itself, melatonin is a key facilitator of the body’s healing. Melatonin enhances cell repair, preventing them from cell death. This effect extends to neural cells as research shows melatonin has neuroprotective benefits. It also reduces acute and chronic inflammation in the body by preventing cytokine release as well as the production of other inflammatory mediators from immune cells.

Melatonin provides critical support to the immune system by coordinating the body’s response against viruses and other pathogens. Research has shown that melatonin production decreases with age and this correlates with the decrease in immune function seen with aging as well. So, getting adequate, restful sleep becomes even more important as we age to ensure melatonin production remains sufficient and immune health is maintained.

How Much Sleep Do I Need?

The amount of sleep you need will depend on several factors. Your age is a significant factor in how long you'll need to sleep per night.

As babies, we need a lot of sleep. Newborn infants may need anywhere between 14 to 17 hours to develop properly and stay healthy, decreasing to 12-15 hours by the first year. By the time we're toddlers, this amount has decreased, but we still need around 11-14 hours a night. Preschoolers should get 10-13 hours, while elementary and middle-schoolers should get nine to 11 hours. Teens need less sleep but still require more than full adults: at least nine or 10 hours.

Once you leave your teens behind, you probably need between seven and nine hours of sleep. While some rare individuals can get by on much less sleep, most people will need at least eight hours to be at their best.

Fixing Your Sleep Cycle

Many things can disrupt your sleep. Besides environmental factors, like nearby traffic or noisy neighbors, many things in our modern lives can make it challenging to get enough good quality sleep. Stress, staying up too late, and conditions like sleep apnea can all lead to sleep deprivation.

In some cases, you may not even be aware that your sleep cycle is being disrupted. For instance, in the case of sleep apnea, you might be waking up several times a night without realizing it. Even if you're not fully awake, you might not be getting quality sleep. Sleep deprivation symptoms might not always be recognized as such since they can be confused with other conditions.

Taking up regular exercise is a great way to improve your sleep and boost your immune system. If stress is a problem, take steps to address it. You could also check in with your doctor to find out if you have any medical issues that keep you awake. With proper interventions, you should be enjoying a healthy night's sleep once more.