A dose of high-intensity exercise in the early evening can enhance your sleep, but working out immediately before bed will have the opposite effect, according to new research by Concordia University. Published in the journal Sleep Medicine Reviews, the research assessed data from 15 published studies to see how highintensity exercise affects young and middle-aged adults in the hours before they hit the sack. So if you normally go to bed at 10pm, give yourself an 8pm end-of-exercise curfew to ensure you improve your sleep instead of disrupting it.