Reflex anoxic seizures occur mainly in children, but it is normal for them to occur at any age. Any unexpected triggers, such as shock or fright, could cause the heart and breathing to stop.
The person’s eyes will roll up, their complexion turn very pale (often blue around the mouth and eyes), their jaw can become clenched and body could stiffen. In some cases, the arms and legs will jerk.
This usually lasts less than a minute. The sufferer’s heartbeat will then continue to beat, their body will relax and they will be unconscious. They could regain consciousness from anywhere between a couple of minutes to over an hour later.
When the person recovers, they could feel extremely tired and may sleep for a few hours.
This is a typical RAS attack. It can occur a few times a day, week or month. The attacks tend to be experienced in batches.
Go through this checklist if you have suffered these symptoms stars.org.uk/files/file/STA...
Tilt Table Test - Advice
Any advice? 
Fainting with no cause 
Fainting with out a warning
