The active control group will receive group-based health-related psychoeducation, a format that has been adopted in the previous research, in order to provide the credibility of the intervention to the participants, and to control for the potential effects of attention and nonspecific components, e.g., receiving health-related information, expectations of benefit. It will also consist of 6 weekly sessions which contain education on general well-being, diet, and exercise/activity.

Daily sleep diary for consecutive seven days. Sleep parameter estimated by daily sleep diary: total sleep time (TST) in hours.

Daily sleep diary for consecutive seven days. Sleep parameter estimated by daily sleep diary: sleep onset latency (SOL) in mins.

Daily sleep diary for consecutive seven days. Sleep parameter estimated by daily sleep diary: sleep efficiency (SE), which is calculated by total sleep time divided by total time in bed, %.

Sleep-wake pattern will be objectively measured by 7-day wrist actigraphy (Actiwatch Spectrum, Philips Respironics). Sleep parameter estimated by actigraphy will include time in bed, total sleep time, sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency.

The Cued Go/NoGo task is a spatial-cueing task with equal probability of Go and NoGo stimuli. In the beginning of each trial, a left or right pointing arrow is presented for 200ms as a cue, instructing the participants to attend to the cued location and ignore the other. Following interval varying from 1000-1200ms from cue offset, a target is presented for 200ms. Participants should respond to the plus sign '+' (Go) at the cued location (Attend-Go), whilst inhibit from responding to the letter 'x' (NoGo) at the cued location (Attend-NoGo). For any target appearing at the ignored location, participants should not respond to either the Go target (Ignore- Go) or the NoGo target (Ignore-NoGo). The percentage of errors in all the trials (total error), the percentage of errors in Attend-NoGo trials (commission errors, indicating inhibition error), and the reaction time in Attend-Go trials with accurate responses (reaction time).

In this task, participants are instructed to fill the balloon with air by selecting number of "pumps" on the dial. Once the number of pumps was selected, the balloon would automatically expand until the target pump number was reached or the balloon popped. Either a green square (indicative of a reward) or a red square and exploded balloon (indicative of loss) appeared after the pumps accompanied by an auditory feedback played 500ms after the visual feedback. Visual feedback lasted 1000ms followed by a 1000-1200ms crosshair and a 100ms blank screen before the next balloon was presented. The total points earned, balloon/trial number, and the explosion point for the last balloon were displayed at the bottom of the screen. After the feedback, a new uninflated balloon appeared on screen until a total of 60 balloons were completed.

In the delay discounting task, participants are asked to choose between two options: an immediate smaller reward (e.g., $17 now) and a later larger reward (e.g., $20 in 5 months). The magnitude of the immediate smaller reward and the magnitude and delay of the later larger reward varies from trial to trial. The immediate smaller option is always smaller and earlier than the later larger option. Performance indicator: The area under the curve (AUC) method will be used to analyse the data. A smaller AUC value indicates a higher impulsive choice.

In the information sampling task, participants are presented with a matrix of 25 gray boxes and 2 larger colored panels (yellow and blue) at the bottom. When participants touch a gray box, it will open to show its color (yellow or blue). Participants are instructed to decide which color they think is in the majority. It is up to the participants how many boxes they would like to open before making the decision. There are two conditions, i.e., Fixed win condition and Decreasing Win condition, each consisting of 10 trials. Performance indicators: The mean probability of being correct at the point of decision (P correct), the mean number of boxes opened per trial, as well as discrimination and sampling errors will be analysed. The lower mean P correct reflects higher reflection impulsivity.

The ERP components including CNV, NoGo N2, and NoGo P3 will be examined between the treatment group and control, in baseline, post-treatment and followup sessions.

The ERP components including feedback-related negativity (FRN) and P300 amplitudes to both negative and positive feedback will be examined on the Balloon Analogue Risk Task.