Which of the following factors are typical examples of the effects on flight crew of short-term, acute fatigue? 

1. Tiredness and falling asleep for short periods without being aware that this happens. 

2. Constant feeling of lethargy and lack of energy. 

3. Reduced concentration and vigilance. 

4. Increased error rate and slowed reaction times.

5. Increased mental and physiological health issues. 

 6. Increased irritability. 

2,4, 5 and 6.