The optic nerve is a bundle of more than 1 million nerve fibers that carry visual messages. You have one connecting the back of each eye (your retina) to your brain. Damage to an optic nerve can cause vision loss. The type of vision loss and how severe it is depends on where the damage occurs. It may affect one or both eyes.

There are many different types of optic nerve disorders, including:

• Glaucoma is a group of diseases that are the leading cause of blindness in the United States. Glaucoma usually happens when the fluid pressure inside the eyes slowly rises and damages the optic nerve.
• Optic neuritis is an inflammation of the optic nerve. Causes include infections and immune-related illnesses such as multiple sclerosis. Sometimes the cause is unknown.
• Optic nerve atrophy is damage to the optic nerve. Causes include poor blood flow to the eye, disease, trauma, or exposure to toxic substances.
• Optic nerve head drusen are pockets of protein and calcium salts that build up in the optic nerve over time

Contact your health care provider if you are having vision problems. Tests for optic nerve disorders may include eye exams, ophthalmoscopy (an examination of the back of your eye), and imaging tests. Treatment depends on which disorder that you have. With some optic nerve disorders, you may get your vision back. With others, there is no treatment, or treatment may only prevent further vision loss.

Almost 1 of every 10 infants born in the United States are premature, or preemies. A premature birth is when a baby is born before 37 completed weeks of pregnancy. A full-term pregnancy is 40 weeks.

Important growth and development happen throughout pregnancy - especially in the final months and weeks. Because they are born too early, preemies weigh much less than full-term babies. They may have health problems because their organs did not have enough time to develop. Problems that a baby born too early may have include:

• Breathing problems
• Feeding difficulties
• Cerebral palsy
• Developmental delay
• Vision problems
• Hearing problems

Preemies need special medical care in a neonatal intensive care unit, or NICU. They stay there until their organ systems can work on their own.

Centers for Disease Control and Prevention

Sciatica is a symptom of a problem with the sciatic nerve, the largest nerve in the body. It controls muscles in the back of your knee and lower leg and provides feeling to the back of your thigh, part of your lower leg, and the sole of your foot. When you have sciatica, you have pain, weakness, numbness, or tingling. It can start in the lower back and extend down your leg to your calf, foot, or even your toes. It's usually on only one side of your body.

Causes of sciatica include:

• A ruptured intervertebral disk
• Narrowing of the spinal canal that puts pressure on the nerve, called spinal stenosis
• An injury such as a pelvic fracture.

In many cases no cause can be found.

Sometimes sciatica goes away on its own. Treatment, if needed, depends on the cause of the problem. It may include exercises, medicines, and surgery.

While you are sleeping your brain and body functions are still active. Sleep is a natural process that helps your body restore energy, supports learning and memory, and keeps you healthy.

It's not just the number of hours of sleep you get that matters. The quality of your sleep is also important. During the night, your brain cycles through different stages of non-rapid eye movement (non-REM) sleep and rapid eye movement (REM) sleep. If your sleep is often interrupted, you may not get enough time in certain stages of sleep. Poor-quality sleep does more than make you feel tired. It can affect your physical and mental health, thinking, and daily functioning.

Sleep disorders are conditions that disturb your normal sleep patterns. There are many types of sleep disorders. Some general types include:

• Insomnia, which is trouble falling asleep or staying asleep.
• Sleep-related breathing disorders such as sleep apnea, a condition in which you stop breathing for 10 seconds or more during sleep.
• Sleep-related movement disorders such as restless leg syndrome (RLS), which involves tingling or prickling sensations in your legs, and a strong urge to move them.
• Hypersomnia, which is extreme daytime sleepiness. This includes narcolepsy.
• Circadian rhythm sleep-wake disorders, which are problems falling asleep or waking up at the right times. This may be due to shift work or jet lag.
• Parasomnia, which is unusual behaviors during sleep or while falling asleep or waking up. This may include sleepwalking, talking, or eating during sleep.

Some people who feel tired during the day have a true sleep disorder, while others simply don't get enough sleep. The amount of sleep you need depends on your age, lifestyle, health, and sleep patterns. Most adults need about 7-9 hours each night.

There are different causes for different sleep disorders. They may include:

• Other health conditions, such as heart disease, lung disease, nerve disorders, or pain
• Mental illnesses, including depression and anxiety
• Medicines
• Genetics

Sometimes the cause is unknown.

Other factors that may contribute to sleep problems include:

• Using caffeine or alcohol
• Having an irregular schedule, such as working the night shift
• Aging, since older adults may sleep less, spend less time in deep sleep, and wake easily

The symptoms of sleep disorders depend on the specific disorder. Some signs that you may have a sleep disorder include that:

• You regularly take more than 30 minutes to fall asleep.
• You regularly wake up several times and then have trouble falling back to sleep, or you wake up too early in the morning.
• You often feel sleepy during the day, take frequent naps, or fall asleep at the wrong times during the day.
• Your bed partner says that when you sleep, you snore loudly, snort, gasp, make choking sounds, or stop breathing for short periods.
• You have creeping or tingling sensations in your legs or arms that are relieved by moving or massaging them, especially in the evening and when trying to fall asleep.
• Your bed partner notices that your legs or arms jerk often during sleep.
• You have vivid, dreamlike experiences while falling asleep or dozing.
• You have episodes of sudden muscle weakness triggered by strong emotions.
• You feel as though you cannot move or speak for a brief time when you first wake up.

To diagnose a sleep disorder, your health care provider will review your medical and sleep history and do a physical exam. You may also have a sleep study (polysomnogram). Most sleep studies monitor and record data about your body during a full night of sleep. The data includes:

• Brain wave activity
• Eye movements
• Breathing rate
• Blood pressure
• Heart rate and electrical activity in the heart and other muscles

Other types of sleep studies may check how quickly you fall asleep during daytime naps or how well you can stay awake during the day.

Treatments for sleep disorders depend on which disorder you have. They may include:

• Practicing good sleep habits and other lifestyle changes, such as eating a healthy diet and getting regular exercise
• Reducing anxiety about sleep with cognitive behavioral therapy or relaxation techniques
• Using a CPAP (continuous positive airway pressure) machine for sleep apnea
• Using bright light therapy (in the morning)
• Taking sleep aid medicines, or natural products such as melatonin

Always check with your provider before taking any medicine or supplement. Most sleep aid medicines are generally for short-term use.

Strep is short for Streptococcus, a type of bacteria that often lives in your nose and throat. Most strep infections are mild, but some may become serious depending on your overall health.

There are several types of strep. Two of them cause most of the strep infections in people: group A and group B.

There are different ways that streptococcal infections may spread:

• Group A strep can be spread from a person who has the infection, even if they don't feel sick, when:
  • They cough or sneeze
  • You share a glass or utensil with them
  • You touch something with the bacteria on it and then touch your eyes, mouth, or nose
  • You touch their open wound or sore
• Group B strep can be passed to a newborn through fluids during a vaginal birth

• Group A strep infections are most common in children ages 5 to 15, but adults can get them too. You may be at higher risk if you have a weakened immune system, open sores or wounds, or certain viral infections such as a cold or flu.
• Group B strep is most often a concern for newborns. Adults can also get group B strep infections, especially those 65 or older or who already have other health problems.

Symptoms depend on the type of infection. Most group A strep infections are mild, but some can be serious.

Group A strep may cause:

• Strep throat. A sore, red throat. Your tonsils may be swollen and have white spots on them.
• Scarlet fever. An illness that follows strep throat. It causes a red rash that spreads across the body.
• Impetigo. A skin infection that causes sores or blisters, often around the mouth, nose, or on the arms and legs.
• Cellulitis. A skin infection that causes redness, swelling, and pain, usually on the legs.
• Necrotizing fasciitis (flesh-eating disease). A rare but serious infection that spreads quickly through the skin and tissue.
• Streptococcal toxic shock syndrome. A rare but life-threatening illness where the bacteria release toxins that can cause organ failure.

Group B strep may cause:

• Blood infections, pneumonia and meningitis in newborns
• Urinary tract infections, blood infections, skin infections, and pneumonia in adults

Group A strep. How strep is diagnosed depends on the type of infection. Your healthcare provider will usually diagnose strep throat with a rapid test or a throat culture. Other strep infections may require a physical exam, lab tests, imaging, or in some cases, surgery.

Group B strep. If you are pregnant, your provider will typically screen you for group B strep around 36 to 37 weeks.

Your treatment will depend on the type of infection:

• Group A strep infections often go away on their own after about a week. If you need treatment, your provider will likely prescribe antibiotics. More serious (invasive) group A strep infections may require you to receive antibiotics in a hospital. Without treatment, these infections can lead to serious health problems.
• Group B strep infections in pregnant women are treated with intravenous (IV) antibiotics during labor to protect the newborn. Adults with group B strep infections are also treated with antibiotics.

You can help prevent some group A strep infections by practicing good hygiene habits, including:

• Avoiding close contact with someone who has an infection
• Washing your hands often with soap and water
• Covering your mouth and nose when you cough or sneeze

To help prevent group B strep infections in newborns, you should get screened during pregnancy. If you test positive, antibiotics given during labor can protect your baby.