In general, 7 1/2 to 8 1/2 hours of sleep at night are enough for most people. If you're getting that much sleep and are still tired, however, it's probably time to evaluate the quality of your sleep. Consider these questions:
- Is your sleep/wake schedule consistent with a set bedtime and awakening time everyday?
- Do you have good sleep hygiene?
- Do you have an undiagnosed sleep disorder that needs to be treated?
If you aren't getting enough quality sleep, you'll typically become tired around 4:00 p.m. Your body's daily rhythm does this naturally around 6 a.m. and 4 p.m., which (not coincidentally) is the time most car crashes occur as people fall asleep at the wheel.