If you're worried to the point where it affects your health, it means you're in to heavy. If it's just concern, well, that's completely normal with any kind of investment.
I think its not normal. If you can't take the heat then you have to get out of the market ASAP because anything worst could happen to you.
with this high prices i only hold bitcoin for short time only.
more ban exchange sites and less interest to buy small amount of bitcoins
Actually if you don't have funds to buy 1
BTC, its better to accumulate then in small parts. And later you you wouldn't realized that you already so much bitcoin that it's more than 1
BTC in your wallet.
I really don't like to worry to much as far as the price of bitcoin goes. For me it will go up in the future. So I just hold my coins, do some trading to earn profit, rinse and repeat.