Participants (n=20) will receive the cognitive training intervention later, following week 8 assessments.

19-item questionnaire that assesses preference for morning, afternoon, and evening activities. Total score reflects degree of "morningness" or "eveningness" type.

Holter monitor assessed 5 min ECG recordings both at rest and during sleep (with PSG).Time index variables: SDNN (standard deviation of normal to normal heartbeat intervals). Spectral index variables: High frequency (0.15-0.4 Hz), low frequency (0.04-0.15 Hz), very low frequency (below 0.04 Hz).

Perceived Stress Scale is a self-report measure of how life situations are perceived as stressful. The scale consists of 15 items corresponding to everyday situation and participants are asked to rate on a likert scale from 0 (never) to 4 (very often) how often they felt or thought a specific way. Higher scores correspond to higher perceived stress.

21-item inventory that asks respondents to rate on a scale of 0 (no depressive feelings) to 3 (most depressive feelings) their feelings towards various aspects of daily living/situations. Higher total scores indicate worse depressive symptoms.

10-item questionnaire that assess the frequency of alcohol use and problems associated with alcohol use over the past year.

Inventory that asks respondents to rate how true 20 self-descriptive statements (e.g., I feel calm) are on a 4-point scale (1 = not at all, 4 = very much so). Typically, respondents are asked to rate statements according to how they generally feel (trait-anxiety scale) and how they feel in the current moment (state-anxiety scale). Total scores range from 20 to 80, with higher scores indicating greater maladjustment.

Pre-sleep Arousal Scale is a 16-item self-report questionnaire comprising both cognitive and somatic manifestations of arousal.

Arousal Predisposition Scale is a 12-item inventory that has been designed to measure the degree to which an individual experiences arousal. Higher scores indicate greater predisposition to arousal.

Electronic Daily Sleep Diaries. Online diaries completed each morning (~5 mins) during 1 wk assessment period and 6 weeks of intervention. Diaries measure sleep onset latency, wake time after sleep onset, total sleep time, and sleep quality.

Brief self-report measure of current perception of insomnia symptom severity, distress and daytime impairment. Commonly used in insomnia treatment outcome research.

Single night PSG measured sleep stages.

During the intervention phase for each group, participants will complete "gaming diary" measuring session duration, games played.