They change - The word “they” in this place, some understand as referring to his friends; others, to his thoughts. Rosenmuller supposes it is to be taken impersonally, and that the meaning is, “night is become day to me.” Wemyss translates it, “night is assigned me for day.” So Dr. Good renders it. The meaning may be, that the night was to him as the day. He had no rest. The period when he had formerly sought repose, was now made like the day, and all was alike gloom and sadness.
The light is short because of darkness - Margin, near. The meaning is, probably, “even the day has lost its usual brilliancy and cheerfulness, and has become gloomy and sad. It seems to be like night. Neither night nor day is natural to me; the one is restless and full of cares like the usual employments of day, and the other is gloomy, or almost night, where there is no comfort and peace. Day brings to me none of its usual enjoyments. It is short, gloomy, sad, and hastens away, and a distressing and restless night soon comes on.”