To better answer this, it is important that you understand how much sleep and exercise you need. Both are considered important pillars of healthy living. A minimum of 7 hours of sleep per night is recommended for an average adult, to maintain a healthy metabolic function, weight and brain health. Sleeping less than this number leads to serious health problems in the long term. On the other hand, maintaining a consistent physical activity, have good health impacts on your body, and failing to do so, also reflects negatively. Furthermore, there is a two-way relationship between sleep quality and physical activity. The latter is able to improve your sleep quality, while a good night's sleep can give you enough energy and stamina to work out well the next day.

While sleep is a biological need for our survival, skipping a few days of working out does not have effects as bad as being sleep deprived. This fact tells you that choosing sleep over working out is not only permitted when you haven’t slept last night but is mandatory. Always choose to sleep when the quality of your last night’s sleep was not good. In all other cases, working out would be a better choice.

Your health is affected more positively by a 30 minutes workout than a 30 minutes nap or extra sleep especially when you did get enough sleep the night before. Therefore, if you have slept for 7 hours, then it would be better to work out rather than extend your sleep.

If during your day, you feel in need of a nap, you can keep it short and get the same benefits from it. Scientists proved that naps as short as 15 minutes can significantly increase your alertness and energy without impairing your next night’s sleep. However, if you are sleep deprived, or haven’t slept well the night before then it will be hard to stop the nap at 30 minutes, therefore rather than napping, go to bed earlier.

Therefore, taking the decision to sleep or exercise depends on how tired or sleep-deprived you are. If you’ve slept well during the night, then exercise and if you haven’t, go to bed. If you’ve slept well but feel very tired, take a short nap without allowing it to extend 30 minutes. You can also do a lighter workout that your tired body can endure.

Regarding being faced with this dilemma right after waking up in the morning, if the time is after 5 a.m. and you can’t fall asleep, then get up and workout. This decision will help you get a full night's sleep the night after.