1. Hyperthyroidism: Excessive sweating, heat intolerance, and irritability are common symptoms. 

2. Diabetes: Autonomic neuropathy can cause increased sweating in the upper body, along with trembling hands and pale complexion.

3. Lymphoma: Both Hodgkin's lymphoma and non-Hodgkin's lymphoma can cause night sweats, low-grade fever, and weight loss.

4. Neurological disorders: Conditions like stroke and abnormalities in the autonomic nervous system can result in increased sweating and night sweats.

5. Infections: Chronic infections, including tuberculosis, endocarditis, osteomyelitis, and abscesses, can present with night sweats as an initial symptom.