In what war? Rudel described one incident in his book as a laughable minor irritation to their nightly activities.
The material effect these raids were rather insignificant but it did have a psychological impact with the night harassment missions. How big of a psychological impact? Not sure but probably along the same levels as the night harassment raids by the Allies and Axis forces.
I know that USAAF squadrons in the Pacific hated it when the Japanese flew harassment missions as it usually resulted in a loss of a night's sleep and increased stress as a result.
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