Lesson 7.2: The Science behind Sleep | Crossword
Across
3. | physical, behavioral, and mental changes in the body that occur naturally and typically follow the 24-hour cycle of the sun |
Down
1. | a hormone released by the pineal gland that increases feelings of relaxation and tiredness |
2. | the fatigue that people experience after changing time zones during travel |
4. | a type of cell that makes up the body’s nerve tissues |