Side effects - Melatonin - linked to nightmares/false awakenings/sleep paralysis?

[PingoTango]

SWIM has recently been taking 5mg melatonin supplements (bought for him by a friend in the US due to it's not being available here in the UK) to combat his bouts of insomnia - he takes one 5mg tablet each night before going to bed, at about 10:30pm. The pills do work, they help him enjoy longer periods of good quality sleep, and enable him to drop off sooner than he normally would.

He has, however, noticed that maybe once a week he will experience terrifyingly vivid nightmares, several false awakenings in a row before actually awakening, periods of paralysis combined with a ringing in the ears immediately after waking up, or (more usually) some combination of the three.

He has been taking the melatonin for maybe a month and has been experiencing these symptoms for maybe two weeks. Is there a link? Any way to negate these side effects?

Thanks in advance...

[humdroid]

There was a little web search carried out by someone who has just gone onto melatonin, and experiences sleep paralysis anyway. (my sausage dog wants to chime in, that he learnt some self knowledge during a ASP episode linked to his patience, and panic, so all is not bad.)
The search carried out above revealed a quote below, from a site related to Awareness in Sleep Paranlysis (ASP for short) about melatonin as an aid to sleep disturbance.

"Consider Melatonin Supplementation Problems with insomnia and the sleeping/waking cycle may respond to melatonin supplements or to melatonin in combination with prescription medications. (In some countries melatonin is itself a prescription medication.)
The relationship between melatonin and ASP is complex and incompletely understood. So, in considering the various threats to your sleeping/waking cycle, we will consider also the extent to which they respond to melatonin supplements.
Melatonin Depletion levels of melatonin in the body decline naturally as we age, and from a wide variety of other causes, including stress"