To date, 16 states have passed medical marijuana laws, yet very little is known about their effects. Using state-level data, we examine the relationship between medical marijuana laws and a variety of outcomes. Legalization of medical marijuana is associated with increased use of marijuana among adults, but not among minors. In addition, legalization is associated with a nearly 9 percent decrease in traffic fatalities, most likely to due to its impact on alcohol consumption. Our estimates provide strong evidence that marijuana and alcohol are substitutes.This really isn't a surprise to me at all. The main reason to do drugs (assuming you aren't an addict) is that you want a break from your current mental state, whether it's to relieve stress, have fun, or just experience something different.
Source: "Medical Marijuana Laws, Traffic Fatalities, and Alcohol Consumption" from IZA Discussion Paper No. 6112 November 2011
There is considerable evidence that humans enjoy altered states of consciousness and seek them out for their own sake, though the methods used differ (running, fasting, drug use, sleep deprivation, traveling, mediation, and listening to music being just a few). In other words, alcohol and marijuana do basically the same thing for their users: it's not surprising that they are interchangable (though it's a pity marijuana isn't legal as its negative side effects are fewer). (Just a disclaimer: I prefer alcohol to marijuana so this is more of a theoretical opinion.)
--Exercise: 30 min. walking.
--Diet: Breakfast: Toast with peanut butter and jam; bread with mayonnaise; Snack: Frappucino, packet of gummy bears; Dinner: Pasta with tomato bacon sauce; Drinks: Chocolate soy milk
--Other: Did not drink 8 glasses water; one frappucino consumed.