If you think that weekend lie-ins, allowing you to catch up on missed sleep during the week, will solve nagging tiredness, it may be a shock to fi nd out that it is diffi cult to ‘pay back’ a large sleep debt. Most adults need between seven and nine hours sleep every night for optimum performance - and maybe even more than our normal average when we’re training intensively. Too much of a sleep debt could lead to changes in mood and health issues, as well as impacting both training and motivation. It’s best to set up a regular sleep routine each evening (no screens, no caffeine, no alcohol) than rely on catching up at the weekend.