enervation

/ˌɛnərˈveɪʃən/
noun
  1. A state of being drained of energy or vitality; physical or mental weakness.
    • The team's enervation was obvious after playing three games in five days.
    • Enervation from overwork can lead to serious health problems.
    • The long illness left him in a state of enervation that lasted for months.