Almost all body functions undergo circadian variations synchronized by light/dark cycle-regulated melatonin secretion from the pineal gland. Circadian disruption reduces melatonin secretion and increases the risk of diabetes and its complications, including anxiety. We aimed to study the effects of reduced daily light exposure on diabetes-associated anxiety-like behavior and brain oxidative stress in streptozotocin-treated rats. Male Wistar rats were divided into the following groups: 1. control (C12/12), saline-treated group with light/dark cycle 12/12h; 2. saline-treated group on light/dark cycle 6/18h (C6/18); 3. diabetic group (100 mg/kg streptozotocin) on 12/12h light/dark cycle (DM12/12); and 4. diabetic group on 6/18h light/dark cycle (DM6/18). Anxiety-like behavior was estimated by elevated plus maze (EPM) and open field test (OFT), while oxidative stress parameters were determined in the cortex, the hippocampus, and the thalamus. Time spent in open arms of EPM was significantly longer in DM6/18 compared with DM12/12 group (p<0.05). Ambulatory distance and time spent in the central area of the OFT were significantly higher in DM6/18 vs. DM12/12 group (p<0.05). Lipid peroxidation, measured as malondialdehyde level, in the hippocampus, cortex, and thalamus, was significantly reduced in DM6/18 compared with DM12/12 group and negatively correlated with the center ambulation distance in OFT and with time spent in open arms of EPM. Reduced light exposure alleviates anxiety-like behavior in streptozotocin-induced diabetes associated with the reduction of oxidative stress. Restricted cell phone and computer usage during the night could be an additional lifestyle measure for the delay of the development of diabetes-associated anxiety.