It’s important to have a policy limiting scheduled work—ideally to no more than 12 hours a day, and exceptionally to no more than 16 consecutive hours. At least 11 consecutive hours of rest should be provided every 24 hours. Furthermore, employees should not be scheduled to work more than 60 hours a week and not be permitted to work more than 80 hours a week.
Naps can be very effective at restoring performance, and if they are brief—less than a half hour—they will induce less grogginess upon awakening.
Human beings are amazingly sensitive to light. In fact, the color of light may also be important. Exposure to shorter wavelength blue light is particularly effective in suppressing melatonin production, thereby allowing us to stay awake during our biological night. Photon for photon, looking up at the blue sky, for example, is more effective in both resetting our biological clock and enhancing our alertness than looking down at the green grass.