Je devais vs j'ai dû

Question

I though devoir in imparfait meant "was supposed to" and in passé composé meant "had to" so shouldn't it be "j'ai dû me lever plus tôt"?

Accepted Answer

Hi Danielle, 
In this exercise, the following hint is given -
'Use devoir, repeated action in the past'
so the imparfait is required. 
In this context, it would not mean 'was supposed to'.
But you would use the P. Composé in the following single event example-
Hier, j'ai dû me lever tôt car on partait en vacances = Yesterday I had to get up early as we were going on holiday.

Answer

It is imparfait because it is describing a habitual action that took place in the past. It's more like "would have to" in this case rather than an action that took place once with "had to" in the case of passé composé - Expressing past habits or repeated actions with the imperfect tense in French (L'Imparfait)