Related Clues:
- Sleep cycle phenomena
- X-ray dose units
- Signs of dreaming
- Reactor units
- Engine coolers, for short
- Sleep cycle occurrences
- Sleep stages
- Radiators or radicals, slangily
- Extremists, for short
- Units of a dangerous dosage
- Units of energy equal to 100 ergs per gram
- Sleep stages, briefly
- Nuclear power plant units
- Nuclear plant units
- Units of energy absorbed