Morningness, or lark trait: People with this trait are naturally "early to bed and early to rise" and tend to have more difficulties working night and evening shifts.
Eveningness, or owl trait: People with this trait are naturally "late to bed and late to rise" and tend to have fewer difficulties working night and evening shifts. They tend to have more trouble with early morning start times.
This trait may have consequences for shift preferences and coping capabilities.
Studies of adult twins give evidence for a genetic link for the morningness/eveningness tendency: about 50% of identical twins are the same on this trait.4,5
Morningness/eveningness tends to change as people age.6 Teenagers and young adults tend to be "evening" types, and researchers theorize this may be due to brain and body development at those ages. Morningness increases as people age, so older adults tend to be "morning" types.
You can fill out the following morningness/eveningness questionnaire7 and see if your answers fit either of these traits. However, sufficient research evidence is not available to support the validity and reliability of a morningness/eveningness questionnaire score to predict a person's ability to adapt to night shift.8,9
Click to open the file with the instrument: Morningness/Eveningness Questionnaire7