1.   Do they result from the body clock, from sleep loss - or from some mixture of these factors?

2.   The biospherians experienced headaches, sleep loss, and fatigue.

3.   Faculty members and program directors will be required to assess the residents for signs of sleep loss and fatigue.

4.   One experiment will study muscle deterioration, the other sleep loss.

5.   One hour of sleep loss a night for a week is the equivalent of pulling an all-nighter, experts say.

6.   Severe and chronic daytime sleep loss may adversely affect brain growth.

7.   The sleep loss was unnecessary.

8.   Thyroid hormone levels were also distorted by sleep loss, but the researchers declined to speculate on the consequences of this abnormality.

9.   Visible fatigue is an acceptable pledge of earnestness and ambition, and there is a reluctance in the business world even to acknowledge the subject of sleep loss.