Transient Insomnia lasts from one night to a few weeks.
Most people occasionally suffer from transient insomnia due to such causes as
jet lag or short-term anxiety. If this form of insomnia continues to occur from
time to time, the insomnia is classified as intermittent.
Acute Insomnia is
the inability to consistently sleep well for a period of between three weeks to
six months.
Chronic Insomnia is regarded as the most serious; persists
almost nightly for at least a month.