Excessive consumption of boiled coffee increases total and LDL cholesterol levels in the blood. Unfiltered coffee is a significant source of cafestol and kahweol, which are diterpenes responsible for coffee's cholesterol-raising effects. The diterpenes are extracted with hot water but retained by a paper filter. This explains why filtered coffee does not affect cholesterol, while boiled Scandinavian coffee, percolator and Turkish coffee do. Additionally, excess caffeine can also overstimulate the central nervous system, disrupting sleep. High amounts of caffeine produce negative effects on the onset and quality of sleep. However, there are large individual differences in the effects of caffeine on sleep. Many people drink coffee in the evening and have no trouble falling asleep, while others find that the mild stimulation of caffeine consumed just before bed delays falling asleep. Finally, a common side effect of coffee that we may all have experienced is tooth staining and dehydration. After a while, without proper care, coffee can stain and permanently damage your teeth. The caffeine contained in coffee is also a mild diuretic and can increase the volume of urine excreted. However, this effect can easily be counteracted by drinking an extra glass