Sleep

Sleep is an essential ingredient in a productive life. Lack of sleep can be a major cause of drowsiness. Several studies also show that even when people don't feel impaired from lack of sleep, their performance is severely degraded.

A few tips:

• Control the environment including temperature, (most people prefer it a little colder when they sleep) light, (keep it off), noise, and more.
• Go to bed and wake up at the same time each day.

Resources

• Book: Why We Sleep by Matthew Walker
• Book: The Promise of Sleep by William C. Dement