The use of water as a force against the skin increases sensitivity in its nerve endings and hence makes the subject feel more awake and alert.

FORBES: Magazine Article

Henman then used his serve and volley attack to lead 3-0 and then 5-2 in the second but his nerve failed him and he allowed Hewitt to claw his way back and force a tiebreaker.

BBC: Henman loses six in a row