David Heinemeier of 37 signals blogged about the impacts to him of working the next day without a normal nights sleep. All of the typical signs were evident: irritability, lack of creativity, decreased performance. Once upon a time, I had a boss that claimed he could operate effectively on 4 hours of sleep. I tried doing that, and after a week I was so tired and ineffective as to be quite useless at work.

After that experience, I did some research on the effects of sleep. Here is a summary of what I learned (thanks to Dr. James Maas in his book “Power Sleep”):

• deep sleep allows the body to restore energy for future performance
• improves immune system; increases resistance to viral infection
• improves memory storage, retention, and organization
• enables learning

The impact of sleep deprivation are as follows:

• daytime drowsiness and/or loss of concentration
• mood changes, such as irritability and depression
• increase in stress and anxiety
• lack of interest in social activities
• weight gain (combination of increase in cortisol production and using food to increase alertness)
• reduced immunity to disease and infection
• loss of motivation
• reduced cognitive functions; in other words, decreased performance

The next time you think that by pulling an all-nighter you will be more productive, think again. Only by getting proper sleep can you be at peak performance.