Insomnia After the COVID-19 Pandemic

Hypothesis/Research Questions H1: What is the level of mental insomnia following three months
of strict mitigation strategies (i.e., physical distancing) in the general adult population
during the COVID-19 pandemic? The mean level of insomnia will be benchmarked against the mean
level of insomnia in similar pre-pandemic samples.

Exploratory: What is the level of insomnia in different demographic subgroups.

H2: The level of metacognition, strategies, worry about job and economy, health-anxiety and
physical activity at T2 will predict insomnia at T2, beyond and above, age, gender, and
education.

Exploratory: Does metacognition, strategies, worry about job and economy, health-anxiety and
physical activity at T1 predict Insomnia at T2, beyond and above psychiatric diagnosis, age,
gender, and education and predictors at T2?

Statistical analysis:

A hierarchical regression analysis will be conducted using BIS as the dependent variable. In
the first step stable characteristics (control variables) will be included: age, gender and
education. In the second step metacognition, strategies, worry about job and economy,
health-anxiety and physical activity at T2 will be included. Part-correlation will be
reported for step 2, presenting the effect size of the predictors on insomnia. In the third
step, anxiety and depression at T2 will be included as control for the variables at the next
step. In the last step metacognition, strategies, worry about job and economy, health-anxiety
and physical activity, at T1 will be included.

Multicollinearity and other statistical assumptions will be checked. Multicollinearity will
be assessed with common guidelines (VIF < 5 and Tolerance > 0.2; Hocking, 2003; O'Brian,
2007). Descriptive statistics with frequency tables including N, means and SDs and other
standard descriptive statistics will be used to examine the level of insomnia. Subgroup
differences will be examined with chi-squared statistics or other statistic based on the
characteristics of the data (e.g. skewness).

All analysis and questions addressed in the forthcoming paper that are not pre-specificd in
this pre-registered protocol will be defined as exploratory.

Sensitivity analyses and random subsample replications of the main finding will be conducted
following selection of a random sample of participants that ensure a proportional ratio
between the collected sample and the adult population in Norway

Measures On the CAS1 four items were combined into the subscale "positive metacognition",
four items were combined into the subscale "negative metacognition", and 8 items were
combined into the subscale strategies (Nordahl & Wells, 2019). Physical activity was measured
with a single item. Worry about job and economy consisted of two items. Health anxiety
consists of four items.

Possible transformations:

All variables will be assessed in their original and validated format as is recommended
practice, as long as this is possible with regards to statistical assumptions underlying the
pre-defined analyses (i.e., multiple regression). However, if this is not possible with
regards to the statistical assumptions behind the analyses, transformation (e.g., square root
or log-transformations) may be needed to apply interval-based methods, alternatively the use
of non-parametric tests.

Inference criteria Given the large sample size in this study, the investigators pre-define
their significance level: p < 0.01 to determine significance.

Sample size:

The present study is part of a larger project with the part aiming to investigate predictors
of sleep trough regression analysis, and the second part aiming to examine directional
relations among specific symptoms and their centrality through network analysis. Thus, the
power calculations are based on power required for network analysis.

Following power analysis guidelines by Fried & Cramer (2017), it is recommended that the
number of participants are three times larger than the number of estimated parameters.
However, more conservative recommendations by Roscoe (1975) for multivariate research,
recommends sample size that is ten times larger than the number of estimated parameters.
Thus, following these two approaches respectively, between 1584 to 5280 participants are
required. Data will be collected for three weeks, and participants are based on a
representative and random sample of Norwegian adults, randomly selected and provided equal
opportunity to partake in the study, providing digital consent.

Eligibility criteria:

Inclusion Criteria:

- Eligible participants are all adults including those of 18 years and above,

- Who are currently living in Norway and thus experiencing identical NPIs, and

- Who had provided digital consent to partake in the study.

Exclusion Criteria:

• Children and adolescents (individuals below 18) Adults not residing in Norway during the
measurement period

Missing data:

The TSD system (Services for Sensitive Data), a platform used in Norway to store
person-sensitive data verifies participants officially through a kind of national ID number
to give them full right to withdraw their data at any time, following the European GDPR
(General Data Protection Regulation) laws. Accordingly, participants are allowed to withdraw
their own data at any time. The survey includes mandatory fields of response. Participation
is voluntarily, and withdrawal of provided data is possible at any moment. We do not expect
participants to withdraw their data and thus expect no missing data. However, if participants
do withdraw their data, we will conduct state-of-art missing data analyses and investigate
whether data is missing at random.

Exploratory:

Questions addressed in the future paper which is not pre-specified will be defined as
exploratory.