The invention relates to N-(2-(substituted-naphth-1-yl)ethyl)-substituted amide compounds, and application of the same as melatonin receptor agonists and 5-HT2c receptor antagonists. Specifically, theinvention relates to the compounds as shown in a formula I which is described in the specification, or pharmaceutically acceptable salts or solvates thereof, or mixtures of the compounds, the salts and the solvates, and pharmaceutical compositions of the compounds, the salts, the solvates or the mixtures. X, R1, R2 in the formula I are as defined in the specification. The compounds as shown in the formula I of the invention can be used as melatonin receptor agonists and 5-HT2c receptor antagonists and is applicable to the preparation of drugs used for treating and / or preventing melatonin system diseases, stress, anxiety, seasonal affective disorders, cardiovascular diseases, digestive diseases, schizophrenia, phobias, depression, major depression, sleep disorders, sleep disturbance, insomnia or fatigue caused by jet lag, weight disorders and other diseases and illnesses.