There is a hell named Andhatamas. The period also of the Sun's southward course is considered as dark. For avoiding that hell and the darkness of this period, one should give lights during that period when the Sun is in northern solstice. Such an act is highly spoken of by the good.
अन्धन्तमस्तमिस्रं च दक्षिणायनमेव च। उत्तरायणमेतस्माज्ज्योतिर्दानं प्रशस्यते॥