If you don’t log at least eight hours of quality shut-eye – the average amount recommended by the Singapore Sleep Society’s website – it’s better to stay in bed. A 2006 study from the University of Hull in England found that sleep-deprived participants who worked out had slower reaction times and were more susceptible to negative moods later in the day. And if you think a workout will wake you up, think again. “Going to the gym when you’re tired will only improve your alertness for a short time,” says Kenneth Wright, PhD, a US-based assistant professor of integrative physiology. On the bright side, opting for the extra shut-eye could actually create time during the day for a workout. When you’re well rested, your productivity and efficiency increase, says Prof Wright. So use that to your advantage by leaving work earlier or taking a longer lunch break to go to the gym.