If you have prior programming experience, R is simple for basic analysis. I don't know of any online tools. The following would be close to sufficient for what you seem to want:

mydata <- read.table("c:/sleepdata.csv", header=TRUE, sep=",") # Read in data w/ variable names in header
fit <- lm(ZQ ~ guess + placebo, data=mydata) # Compute linear regression
summary(fit) # Get estimated coefficients with t-statistics and p-values

For cookbook code, see Quick R. If you do use R, the RStudio IDE is very useful.