Symptoms:

The most common symptoms  are numbness, weakness, tingling or pain felt in the fingers or the palm of the hand.  Symptoms can occur in both hands, but are usually worse in one hand or the other.  People  often notice symptoms at night, waking with pain or numbness.  Other symptoms  include numbness or pain that gets worse while gripping an object or flexing the wrist and/or loss of pinch strength between the thumb and index finger.

Causes: 

The pressure on the median nerve in your wrist.  The median nerve runs from your forearm to your hand through a small space in your wrist called the Carpal Tunnel.  The median nerve controls movement and feeling in the thumb and the first three fingers.  Conditions that can lead to include:

Repetitive movement of the wrists

Arthritis

Diabetes

Obesity

Wrist injuries