How food and drink affect your sleep. What you eat and drink before bed can affect your sleep. For example, foods containing the amino acid tryptophanâa building block of the sleep-related chemical serotoninâcould potentially make you drowsy, although evidence is mixed as to whether the amount in food is enough to change your sleep.
The study estimates lifetime societal savings (net present value) of about $12 billion from the more than 600,000 total knee replacement surgeries performed each year in the U.S. These societal savings primarily accrue to patients and employers.
The Encyclopedia of Surgery says that the number of gender reassignment procedures conducted in the United States each year is estimated at between 100 and 500. The number worldwide is estimated to be two to five times larger.. At least one other researcher says there are many more.