One of the primary causes of finger numbness is poor positioning of your hand. The two main nerves supplying the hand (median and ulnar nerves) run close to the skin surface at certain points. That’s where they are susceptible to temporary injury. 

The median and ulnar nerves are close to the skin at the wrist joint. The ulnar nerve is also close to the skin at the elbow. This means if you press on your wrist or elbow (or bend them) for prolonged periods of time, you can temporarily damage one of the nerve. Leaning on you elbow or “funny bone” which causes pinky numbness is an example.

The commonest way to damage these nerves is when you sleep. Cradling your head or pushing your elbows into the mattress (while sleeping on your back) are easy ways to cause temporary nerve damage and subsequent finger numbness. Of course, adjusting your sleeping position can eliminate the finger numbness.

A stroke (also called "cerebrovascular accident" or CVA) means there's insufficient blood going to part of your brain. Finger or hand numbness due to stroke is unlikely, but it’s also very serious. If the numbness is sudden and you have any of the other symptoms listed below, call your doctor or emergency services immediately. Rapid response can save your life. 

Remember the acronym B.E.F.A.S.T. as follows:

• B = Balance: Does the person feel a sudden loss of balance? Are they having difficulty walking? 
• E = Eyes: Does the person have blurry/double vision, trouble seeing, or vision problems without pain?
• F = Face drooping: Does one side of the person’s face or mouth seem lower than the other (see picture)?
• A = Arm weakness: Does the person have weakness in one or both arms?
• S = Slurring speech: Is the person having trouble speaking or is it hard to understand them (they may sound drunk).
• T = Time to call 911: If any of the above happens, get medical attention fast. Call 911. Say you think it’s a stroke so the hospital can prepare a team.

Carpal tunnel syndrome is caused by damage to the median nerve. Therefore, the hand or finger numbness (left hand or right hand) will occur where the median nerve is present, as shown by the diagram.

When carpal tunnel syndrome first begins, the numbness usually is most pronounced at night, while trying to sleep. As the condition advances, the numbness persists into the daytime.

Other symptoms associated with more advanced or "severe" carpal tunnel are finger or hand pain, burning, shooting electric shocks, hand weakness, hand clumsiness, and loss of dexterity.

Similar to carpal tunnel syndrome, cubital tunnel syndrome causes hand or finger numbness. But it results from damage to the ulnar nerve. This causes finger numbness (left hand or right hand) in the little finger and half of the ring finger.

The ulnar nerve is also the nerve that runs close to the skin at the elbow. This "funny bone" reacts when you lean on it for a long time (or hit it), resulting in tingling on the pinky side of your hand.

Other symptoms of cubital tunnel syndrome are forearm pain. Weakness in the hand is also common, primarily when the elbow is bent. 

Treating cubital tunnel syndrome depends on its severity. Mild conditions can be treated with physical therapy and massage. More severe conditions may require surgery.

Thoracic outlet syndrome is a term used for several different disorders that affect the blood vessels and nerves in the neck and shoulders. It's thought to originate as a repetitive stress injury that results in compression of the thoracic outlet. This is the opening between your upper chest and lower neck, through which nerves and blood vessels pass. 

The compression around the thoracic outlet presses against the blood vessels or nerves. This results in pain, swelling, tingling, and finger numbness (left hand or right hand). Symptoms are especially pronounced when you raise your arms. 

Thoracic outlet syndrome is a very common disorder, affecting up to 8% of the population.  And it's more common in women than men.

Diabetes creates problems all over the body. It results in starving the nervous system of nutrients. This causes nerve damage or neuropathy (more accurately, "diabetic neuropathy").

Diabetic neuropathy can cause hand or finger numbness in the left or right hand (or both). However, sometimes the entire arm is involved. Other times, the numbness may be in the feet and toes. 

Other symptoms of diabetic neuropathy may include:

• Weakness
• Pain
• Burning
• Pins and needles
• Loss of balance

Diabetic neuropathy can be treated with some success using medicines. Additionally, by reducing the symptoms of diabetes, the neuropathy also diminishes. This occurs with good glucose management, proper diet, regular exercise, and medicines, 

Nerves require vitamin B (especially B12) to stay healthy. So, a B vitamin deficiency can lead to nerve injury. That results in hand or finger numbness (left hand, right hand, both feet).

Usually, vitamin B12 deficiency includes other symptoms such as:

• Fatigue
• Weakness
• Yellowing of the eyes and skin
• Difficulty thinking and processing
• Difficulty walking and balancing
• Hallucinations

Magnesium and potassium deficiency are also known to result in numbness when blood levels are low. Vitamin B12, magnesium, and potassium can be supplemented orally. Usually, numbness will diminish or disappear afterward.

A number of medicines are known to cause neuropathy. They result in hand or finger numbness (even foot numbness). It's a side effect of the medicine, and doctors usually warn patients of the potential problem.

Nerve damage (neuropathy) can be a side effect of drugs that treat everything from cancer to seizures. It can affect both your hands and feet.

The drugs most commonly recognized to cause hand or finger numbness (left hand or right hand) include:

• Anticancer drugs (cisplatin and vincristine)
• Antibiotics (metronidazole [or Flagyl], nitrofurantoin [or Macrobid], fluoroquinolones [or Cipro])
• Anti-seizure drugs (phenytoin [or Dilantin])
• Heart & blood pressure drugs (amiodarone [or Nexterone], hydralazine [or Apresoline])

Most people have other symptoms of nerve damage caused by medicines (or drug-induced neuropathy). These include:

• Tingling
• Weakness
• Abnormal feelings in the hands

Cervical spondylosis is a general term that includes wear and tear of the spinal disks in your neck due to age. The disks eventually dehydrate and shrink. This creates signs of osteoarthritis and bone spurs.

Cervical spondylosis is very common, and it gets progressively worse. It's estimated that over 85% of people over 60 years old are affected by it to some degree.

Most people experience no symptoms from cervical spondylosis. But when symptoms do occur, several non-surgical treatments can be effective.

People with cervical spondylosis frequently experience some of the following additional symptoms:

• Weakness in the hands, arms, feet and legs
• A popping sound when moving the neck
• Headaches
• Muscle spasms in the shoulders or neck
• Loss of coordination and balance
• Losing control over the bladder or bowels

Raynaud's phenomenon (or syndrome) can cause finger numbness (left hand or right hand). Even your toes can get numb due to this disorder. 

It usually occurs as a feeling of coldness along with numbness if you're exposed to emotional stress or cold temperatures. Also, the tips of the fingers become blanched or white, causing "white finger" as in the photo.

The cause of this disorder originates in the small blood vessels in your skin. They narrow in diameter (called "vasospasm"), which limits blood flow to the skin. This results in paleness, coldness, and numbness. Often, pain accompanies these symptoms.

Doctors treat Raynaud's disease depending on how severe it is. It also depends on what other health problems you may have. 

Drinking alcohol in moderation is generally safe. But too much alcohol intake can be toxic. It may result in tissue damage all over the body. 

Nerves are especially susceptible to alcohol toxicity. That's why people who drink in excess, especially chronically, risk nerve damage. This can result in tingling or numbness in the fingers, hands, and feet.

The other symptoms of alcohol-related neuropathy are:

• Muscle weakness
• Pins and needles feeling
• Erectile dysfunction
• Muscle spasms or cramps
• Difficulty controlling urination

The alcohol toxicity can usually be alleviated by reducing or eliminating the alcohol intake. Certain medicines can also help manage the symptoms.