I'm with R41 -- 40 was the beginning of being middle-aged.. But my 50's have shown me it really is the beginning of the end. I had an sports injury @ 50 that made it difficult for me to exercise, and I put on 20 lbs. The knee surgery I had to try to correct it only left things worse.
According to the National Institute of Neurological Disorders and Stroke (NINDS), the sudden, involuntary jerking of a muscle or group of muscles while drifting off to sleep is called myoclonus. It is caused by sudden muscle contractions, also known as positive myoclonus, or muscle relaxation, which is referred to as negative myoclonus.
Causes of sleep deprivation Common causes of sleep deprivation include: Personal choice â some people donât realise that the body needs adequate sleep. Instead of regularly going to bed at a reasonable hour, they prefer to stay up late to socialise, watch television or read a good book.