Sleep is the most overlooked part of our lives. When someone wants to get in shape and perform at his best, they first think of eating a healthier diet and then working out. Sleep is never really included in their master plan to achieve peak performance. However research from all around the world proves that mastering sleep is indeed the most important thing you could do to maximize your well-being and your performance.

Sadly the society we grow up in has us thinking about sleep as something that simply just naturally happens. We are never taught why we need to sleep and what happens if we don’t sleep enough. Thus the best teacher of what happens when you fail at getting a good night of sleep is when you pull an all-nighter.  Everyone has done it at least once. You feel like you just got hit by a train. Your performance goes down, your ability to concentrate and work on things plummets, your reaction time gets slow and you might even take longer to think and complete your sentences. Research from the University of Pennsylvania studied exactly what happens to your performance in 4 different cases according to how much sleep each group of participants would get each night:

  1. The first group didn’t sleep for 72 hours straight.
  2. The second group slept for 4 hours each night.
  3. The third group slept for 6 hours each night.
  4. The fourth group slept for a full 8 hours each night.

The test these groups were subjected to might seem easy: they had to press a button whenever a corresponding light came on a screen within a specified time limit. The test lasted for 10 minutes and it was repeated for 14 days (except for group 1 of course). On day 1 every group got a full 8 hours of sleep to test the baseline performance. The researchers recorded the responses and the reaction time from when the participants saw the light to when they had to press the right button.

The results showed disastrous performance impairment for all 3 groups that were sleep deprived. The fourth group which was always well rested maintained a stable, almost perfect performance every time they were tested.

In general the first 3 groups were all affected by sleep deprivation which slowed their reaction time. However the scary finding was that there would sometimes be completely missed responses as the participants would just freeze and stop responding. This phenomenon is called a microsleep: it lasts for a few seconds in which you close your eyes (sometimes fully) and your brain stops responding to the outside world all together. The sad part is, most times you don’t even notice it.

After the first night without sleep, group 1 suffered an increase in missed responses of about 400% compared to their baseline. Their missed responses kept getting worse after 48 hours and 72 hours of no sleep.

The performance of the second group, after sleeping for 4 hours a night for 6 days straight, matched exactly the performance of group 1 after not sleeping for 24 hours. This means a 400% increase in missed responses. After 11 days their performance was the same as group 1 after pulling 2 all-nighters. This means that even though they were sleeping 4 hours every night, after 11 days of doing so their performance was the same as someone’s who had not slept for 48 hours.

The third group, after sleeping for 6 hours a night for 11 days, suffered the same decrease in performance as group 1 after pulling anĀ all-nighter. This means that if you sleep just 6 hours a night for 11 days, you will perform exactly like someone who doesn’t sleep for 24 hours.

The most dangerous finding was that when the participants were asked whether they perceived the level of their performance impairment, they always underestimated how bad it was and how much they were affected by sleep deprivation. Continuously failing at recognizing how sleep deprivation is affecting your performance leads to your body and brain getting used to performing poorly, having low energy levels and lower alertness. This means that your poor performance becomes your baseline. It is as if you forget what it means to perform at your highest levels when you constantly get a full night of sleep. This leads you to never maximizing your mind and body’s potential.

After working with dozens of businessmen and entrepreneurs who were always busy with clients, work, family or simply just running their companies, I assure you that your body fails at making the connection of poor performance to poor sleep habits. Some of my clients were convinced they could sleep 5 hours a night during their workweek, then “sleep it off” during the weekend and make up for their lost sleep and recover their performance. However going back to the study, when the same participants from the first 3 groups were allowed to get a full night of sleep for 3 days straight, their performance did not return to their baseline level when they were tested on day one of the study. This means that if you plan on recovering your sleep during the weekend after not sleeping enough during the week, it will not be enough.

So you might be wondering how many hours you actually need to sleep every night. 

Well, another study from the Walter Reed Army Institute of Research studied the impairments of sleep deprivation on groups of people sleeping 3, 5, 7 and 9 hours. The results were similar to the ones described in the above research, which confirm that even 7 hours of sleep are not enough if you want to achieve peak performance. 

In conclusion, your body needs at least 8 hours of sleep to perform at its best.