The distractions of constant emails, text and phone messages are a greater threat to IQ and concentration than taking cannabis, according to a survey of befuddled volunteers.

Doziness, lethargy and an increasing inability to focus reached “startling” levels in the trials by 1,100 people, who also demonstrated that emails in particular have an addictive, drug-like grip.

Guardian Unlimited | Online | Emails ‘pose threat to IQ’