5. Dehydration
Dehydration causes muscle spasm because it leads to an electrolyte imbalance, altering the way that muscles are signaled to contract and resulting in twitching. This is why you will often feel cramp in the night when you are dehydrated and the same issue can also lead to twitching for the eyes and for other muscles.
Dehydration can be solved simply by drinking water more frequently and especially before bed. This is important considering that a large percentage of the population is actually dehydrated. Likewise, consider using an isotonic drink and especially following exercise.