Something must not good or not correctly happen with you .You first search your cause for mental restlessness.Keep your focus on single work ,multifunction is not helpful here.Any anxiety related issu,mental disturbance,emotional disturbance are the causes of your problem.
Next Steps
1.regular sleep atleast 8 hours
2.Avoid pc or laptop and mobile 1 hour before sleep.
3.morning walk,gym,exercise,swimming makes your anxiety reduced and physically fit