Antidepressants cause fatigue and tiredness. Anti – depressants have depressant effect on our nervous system. So you might feel fatigued, tiredness and sleepy. This is absolutely normal. There is no need to investigate it. Once you stop taking these drugs, your problem of fatigue will resolve. And this is seen in early stage of treatment and slowly resolves. You can drink coffee every eight hours. It might keep you alert in day time. But try to avoid driving and swimming. Anti-depressants also cause insomnia. So if you take it in night you may suffer from sleep problems. But you can take trial by taking at bed time. It might suit you. Thanks