Two of the largest ligaments of the wrist are the medial (ulnar) and lateral (radial) collateral ligaments. The MCL passes from the distal end of the ulnar and crosses the wrist to attach to the triquetrum and the pisiform. The LCL passes from the end of the radius, across the joint to the scaphoid.
One of these can be dehydration. Most people in Britain don't drink as much fluid as they need for optimum health. Although, over time, they may inadvertently train themselves not to feel thirsty, the suppressed desire to drink can result in restlessness and a host of minor problems that make sleep difficulties worse.
The reason for this is because as time progresses during sleep, the alcohol is metabolized, and so you lose the sedative benefit that it provides. In addition, alcohol can really disrupt a stage of sleep called as REM sleep, and the predominance of REM sleep occurs during the latter part of the sleep cycle.